知识是为了幸福，动物求知以避难，人类却反而因为自我设限，不能求知来让自己过得更好。一个充满偏见（被传统自我设限）的人称不上有知识的人。摆脱偏见、善用知识，追求幸福吧。
真理
如果没有命运可以顺从，人是否至少还有真理标准可以随顺呢？就是对于世界万物和人类伦理价值唯一一种正确的理解、唯一一种值得追求的价值标准呢？
关于真理是否存在？伊比鸠鲁的回答是：真理未必存在，在某些事情上，确定的真理是不可能的，我们必须满足于承认事件的起因，有许多自然的可能性。不过如果真理存在，真理是可以通过感官、预期以及痛苦和快乐的感觉清楚地建立起来的。 理性是极其宝贵的，但它依赖于感官来验证真理。在概念维度的世界里，不存在仅靠理性才能获得的更高真理，复杂的三段论推理也不是通往真理的关键（Cicero, On Ends, Epicurean Speaker）。
知识的价值
如果了解伊比鸠鲁的哲学体系，或是他的伦理观，会了解到“知识”对他来说是架构体系的工具和通向人生康庄大道的导引，但不是目的本身。
目的是“幸福”，达成的方法是“美德”，为了要实行美德，并了解为何如此，一个人需要有“智慧”。由此可见，知识不是伊比鸠鲁哲学中终极目的，但是几乎占据最重要的地位。
在《在雅典的几天中》，伊比鸠鲁主义哲学家借伊比鸠鲁的口，对知识有如下颂赞：“知識，是人所能擁有的最好的財富。沒有它，人就是個畜生，有了它，人就是一個神。但就像幸福一樣，人常常追求卻找不到；或者，充其量只是獲得它，但只是不完美的一瞥”。
对于一名接受演化论是自然科学事实，而以此来树立世界基本观点的人来说，我对伊比鸠鲁的主次排序拳拳服膺。所有生物都追求幸福，我也认为人不能自外于这样的基本规律。人可以有玄妙的奇想，但考虑人深层的追求和动机时，不能脱离基本自然事实（很高兴的，伊比鸠鲁似乎也是用相似的知识手法，得出他以幸福为人生最高目的的结论的，即，他考虑行为实际的后果，尽力观察和探索，避免空穴来凤的人生意义理论，从而提出一套朴实无华不高大上的哲学系统）。因此，我相信人也是以追求幸福为目的的。
人追求幸福，幸运的是，人类不仅与所有动物一样，具有行动能力可以避开灾害，追求舒适的生活条件；人类还是有意识的生物中，反省能力别树一帜的存在，我们研究了人与自然、人与社会的关系，我们看出了一些特别的幸福之道——一些未经反思不容易了解的方法，我们因此可以用我们的智慧，指导我们过幸福的生活。
求知的方法——先修步骤：摒除偏见
[I]f he have not cleared the mist of all prejudices from his understanding; if he have not rubbed off all intolerance from his judgments; if he know not to weigh his own actions, and the actions of others, in the balance of justice — that man hath not knowledge; nor, though he be a man of science, a man of learning, or an artist, he is not a sage. He must yet sit down, patient, at the feet of philosophy. With all his learning, he hath yet to learn, and, perhaps, a harder task, he hath to unlearn. (A few dats in Athens, Chapter 9)
“If it be so, these useful qualities have not been attained without much study and discipline; for Zeno is mistaken in thinking all my virtues the children of temperament. I very early perceived candor to be the quality the most indispensable in the composition of a philosopher, and therefore very early set my whole efforts to the attaining of it. And when once I fairly engaged in the work, I did not find it either long or difficult. I had naturally a mild temper, and a sensitive heart, and these gifts were here of inconceivable use to me. Feeling kindly towards my fellow creatures, I could the easier learn to pity rather than hate their faults; to smile, rather than frown at their follies. This was a great step gained, but the next was more difficult — to be slow in pronouncing what is a fault, and what is a folly. Our superstition would haunt with the furies the man who should take his sister to wife, while the customs of Egypt would commend them. How has the astronomer been laughed at, who made the earth revolve round the stationary sun; and yet who can say but the age may come, when this shall be established as a truth? Prejudices, when once seen as prejudices, are easily yielded. The difficulty is to come at the knowledge of them. A thousand lectures had I read to myself, ere I could calmly say, upon all occasions, it does not follow that the thing is, because I think it is; and till I could say this, I never presumed to call myself a philosopher. When I had schooled myself into candor, I found I was possessed of forbearance; for, indeed, it is hardly possible to possess the one without the other.” (A few dats in Athens, Chapter 9)
求知的方法——知识论：知识的基础是经验
對於伊比鳩魯學派而言，知識的基礎就是”所有經驗所察覺的事物“，换句话说，即，「所有經驗所察覺的事物皆為真」‘all sensations are true’。這裡所謂的「真」，是"表徵"的真，而不是命題的真。這個意思是說， 經驗所察覺的內容，就是「真實世界」的表徵，而不需要從語言句型中來檢驗真值（這是斯多噶學派的觀點）。
以視覺為例。當我們在看時，影像不斷地脫離其所屬的個體，流向我們的眼睛，而眼睛也機械式地接收這些流入的原子，再轉換成影像，或針對流入的資料進行詮釋。這些最基本的影像資料，就如同照片一般，不會出錯，而且本身即成為具有證據性的價值（如同「法條」(Canonic)一般）。這種感官的「照相功能」的信賴度，也就是使得感官的察覺不但可以產生真實，而且其本身就因為這種察覺外在世界的機制，而成為知識的標準。
但是，從這裡推理成為外在事物本身的過程，包含判斷能力的展示，也就是在這個階段， 知識有可能出錯。
感官知覺(Sensations) 是伊比鳩魯學派三大知識標準之一。另外兩種是感覺(feelings)（這是用來做出有關價值與心理狀態判斷的要素）以及直覺(prolēpsis)，這是先天因為自然而獲得的知識標準。一個感官知覺是靈魂中，透過機械而且有意識的反應方式，察覺某一外在事物在現象中所呈現外表之觀察。第二種知識的標準是，「直覺」 prolēpsis, or ‘preconception’ 。對於一件事情的「直覺」，是對這件事物本質的直接掌握，並因而掌握這件事物的內容，成為概念分析的對象。第三種真理標準是感覺(pathē), 可以進一步分為兩類： 享樂與痛苦（苑举正：伊比鸠鲁“知识论”）。
苑举正讲义：除了判断能力可能出错，嚴格來講，因為原子論的關係，沒有哪兩個感官知覺會是可以共量的(commensurable)，这可能也造成知识基础没有绝对的统一。
读者可能会想到，科学告诉我们感官是相对的，例如以下三点，一是，灰色在白色旁边会产生黑色的错觉，而在黑色旁边会产生白色的错觉；其二，不同动物因为视觉器官接收器的接受波长限制，看出去的颜色都不同；其三，画面成像仰赖大脑这个黑箱里的器官对于视觉神经传递进来的电子讯息的解读，婴儿看出去的世界先是黑白的，然后是模糊的，然后才是我们看到的世界。
但这不让人怀疑感官经验作为知识“可信”的基础。譬如，人的眼睛看不到原子的结构，但，借助科技的手段、实验的手法，另辟蹊径，人们依旧可以由可获得的经验，建立可靠的知识。初阶的感官经验，可能出错，得到错误的推论，但通过反省和改正，人仍然可能探寻到真理（即便只是局部）。
求知的方法——敢于求知
伊比鸠鲁重视以感官为基础的求知，避免人落入虚无和不可知，而能尽力探索。人在判断知识的时候可能有所偏误，但人还是应该用上自己可以有的去理解知识。
人类有那么灵敏的感官能力和思辨素质，却毫不信任自己、毫不用以求知，宁可盲从听信他人，无异自戕！
Man alone, the most gifted of all known existences, doubts the evidence of his superior senses, perverts the nature and uses of his multiplied faculties, controls his most innocent, as well as his noblest impulses, and to poison all the sources of his happiness. To what are we to trace this fatal error, this cruel self-martyrdom, this perversion of things from their natural bent? (A few days in Athen, Chapter 16)
应用事实和物理学知识，善于考察行为的结果，我们可以获致自然科学和伦理哲学的知识。丢弃那些想象、理论和未经判断的信仰吧！
We have exhorted you to use your eyes, and your judgments, never your imagination; to abstain from theory, and rest with facts; and to understand that in the accumulation of facts, as regards the nature and properties of substances, the order of occurrences, and the consequences of actions, lies the whole science of philosophy, physical and moral. (A few days in Athen, Chapter 16)
Letter to Herodotus: In the first place, Herodotus, you must understand what it is that words denote, in order that by reference to this we may be in a position to test opinions, inquiries, or problems, so that our proofs may not run on untested ad infinitum, nor the terms we use be empty of meaning. For the primary signification of every term employed must be clearly seen, and ought to need no proving; this being necessary, if we are to have something to which the point at issue or the problem or the opinion before us can be referred. Next, we must by all means stick to our sensations, that is, simply to the present impressions whether of the mind or of any criterion whatever, and similarly to our actual feelings, in order that we may have the means of determining that which needs confirmation and that which is obscure.
Letter to Herodotus: And whatever presentation we derive by direct contact, whether it be with the mind or with the sense-organs, be it shape that is presented or other properties, this shape as presented is the shape of the solid thing, and it is due either to a close coherence of the image as a whole or to a mere remnant of its parts. Falsehood and error always depend upon the intrusion of opinion when a fact awaits confirmation or the absence of contradiction, which fact is afterwards frequently not confirmed or even contradicted following a certain movement in ourselves connected with, but distinct from, the mental picture presented—which is the cause of error.
Letter to Herodotus: For the presentations which, for example, are received in a picture or arise in dreams, or from any other form of apprehension by the mind or by the other criteria of truth, would never have resembled what we call the real and true things, had it not been for certain actual things of the kind with which we come in contact. Error would not have occurred, if we had not experienced some other movement in ourselves, conjoined with, but distinct from, the perception of what is presented. And from this movement, if it be not confirmed or be contradicted, falsehood results; while, if it be confirmed or not contradicted, truth results. And to this view we must closely adhere, if we are not to repudiate the criteria founded on the clear evidence of sense, nor again to throw all these things into confusion by maintaining falsehood as if it were truth.
Letter to Herodotus: Further, we must hold that to arrive at accurate knowledge of the cause of things of most moment is the business of natural science, and that happiness depends on this (viz. on the knowledge of celestial and atmospheric phenomena), and upon knowing what the heavenly bodies really are, and any kindred facts contributing to exact knowledge in this respect. Further, we must recognize on such points as this no plurality of causes or contingency, but must hold that nothing suggestive of conflict or disquiet is compatible with an immortal and blessed nature. And the mind can grasp the absolute truth of this. But when we come to subjects for special inquiry, there is nothing in the knowledge of risings and settings and solstices and eclipses and all kindred subjects that contributes to our happiness; but those who are well-informed about such matters and yet are ignorant—what the heavenly bodies really are, and what are the most important causes of phenomena, feel quite as much fear as those who have no such special information—nay, perhaps even greater fear, when the curiosity excited by this additional knowledge cannot find a solution or understand the subordination of these phenomena to the highest causes.
Letter to Herodotus: Hence we must attend to present feelings and sense perceptions, whether those of mankind in general or those peculiar to the individual, and also attend to all the clear evidence available, as given by each of the standards of truth. For by studying them we shall rightly trace to its cause and banish the source of disturbance and dread, accounting for celestial phenomena and for all other things which from time to time befall us and cause the utmost alarm to the rest of mankind.
Letter to Pythocles: We do not seek to wrest by force what is impossible, nor to understand all matters equally well, nor make our treatment always as clear as when we discuss human life or explain the principles of physics in general—for instance, that the whole of being consists of bodies and intangible nature, or that the ultimate elements of things are indivisible, or any other proposition which admits only one explanation of the phenomena to be possible. But this is not the case with celestial phenomena: these at any rate admit of manifold causes for their occurrence and manifold accounts, none of them contradictory of sensation, of their nature.
Letter to Pythocles: For in the study of nature we must not conform to empty assumptions and arbitrary laws, but follow the promptings of the facts; for our life has no need now of unreason and false opinion; our one need is untroubled existence. All things go on uninterruptedly, if all be explained by the method of plurality of causes in conformity with the facts, so soon as we duly understand what may be plausibly alleged respecting them. But when we pick and choose among them, rejecting one equally consistent with the phenomena, we clearly fall away from the study of nature altogether and tumble into myth. Some phenomena within our experience afford evidence by which we may interpret what goes on in the heavens. We see bow the former really take place, but not how the celestial phenomena take place, for their occurrence may possibly be due to a variety of causes. However, we must observe each fact as presented, and further separate from it all the facts presented along with it, the occurrence of which from various causes is not contradicted by facts within our experience.
Letter to Pythocles: The wanderings of certain stars, if such wandering is their actual motion, and the regular movement of certain other stars, may be accounted for by saying that they originally moved in a circle and were constrained, some of them to be whirled round with the same uniform rotation and others with a whirling motion which varied; but it may also be that according to the diversity of the regions traversed in some places there are uniform tracts of air, forcing them forward in one direction and burning uniformly, in others these tracts present such irregularities 4s cause the motions observed. To assign a single cause for these effects when the facts suggest several causes is madness and a strange inconsistency; yet it is done by adherents of rash astronomy, who assign meaningless causes for the stars whenever they persist in saddling the divinity with burdensome tasks. That certain stars are seen to be left behind by others may be because they travel more slowly, though they go the same round as the others; or it may be that they are drawn back by the same whirling motion and move in the opposite direction; or again it may be that some travel over a larger and others over a smaller space in making the same revolution. But to lay down as assured a single explanation of these phenomena is worthy of those who seek to dazzle the multitude with marvels.
Cicero, On Ends, Epicurean Speaker: Hence Epicurus refuses to admit any necessity for argument or discussion to prove that pleasure is desirable and pain to be avoided. These facts, be thinks, are perceived by the senses, as that fire is hot, snow white, honey sweet, none of which things need be proved by elaborate argument: it is enough merely to draw attention to them. (For there is a difference, he holds, between formal syllogistic proof of a thing and a mere notice or reminder: the former is the method for discovering abstruse and recondite truths, the latter for indicating facts that are obvious and evident.) Strip mankind of sensation, and nothing remains; it follows that Nature herself is the judge of that which is in accordance with or contrary to nature.
下回预告
因为伊比鸠鲁开放的心态，和立足于生活经验之上的详细考察，他将不同于其他人，带给我们他独特的伦理系统：
溫和的伊壁鳩魯如是說【注解】，他視人為真：帶著他所有的軟弱，所有的錯誤，所有的罪孽，仍然與他相交，仍然為他的幸福而高興，為他的不幸而歎息；我從我的花園裡向那些沒有思想的人、任性的人和無所事事的人谈话——“你們在哪裡徘徊，你們在尋找什麼？是快樂嗎？看這裡。輕鬆嗎？進入並休息。我就這樣從醉酒的餐桌和放蕩的床上向他們求愛：我輕輕喚醒他們沉睡的官能，從他們的理解中揭開面紗：——“我的孩子們！你尋求快樂嗎？我也找她。讓我們一起進行搜索。(《在雅典的几天》，第7章)
【注解】与之相对：崇高的芝諾如是說，他只看到他應該是的人。