Don't worry about death;
What is good is easy to get, and
What is terrible is easy to endure.
The "Tetrapharmakos" [τετραφάρμακος], or "The four-part cure" of Epicurus, from the "Herculaneum Papyrus", 1005, 4.9–14 of Philodemus, as translated in The Epicurus Reader: Selected Writings and Testimonia (1994) edited by D. S. Hutchinson, p. vi
Luxurious food and drinks, in no way protect you from harm. Wealth beyond what is natural, is no more use than an overflowing container. Real value is not generated by theaters, and baths, perfumes or ointments, but by philosophy.
Let no one be slow to seek wisdom when he is young nor weary in the search of it when he has grown old. For no age is too early or too late for the health of the soul. And to say that the season for studying philosophy has not yet come, or that it is past and gone, is like saying that the season for happiness is not yet or that it is now no more. Therefore, both old and young alike ought to seek wisdom, the former in order that, as age comes over him, he may be young in good things because of the grace of what has been, and the latter in order that, while he is young, he may at the same time be old, because he has no fear of the things which are to come. So we must exercise ourselves in the things which bring happiness, since, if that be present, we have everything, and, if that be absent, all our actions are directed towards attaining it.
Variant translation: Let no one delay to study philosophy while he is young, and when he is old let him not become weary of the study; for no man can ever find the time unsuitable or too late to study the health of his soul. And he who asserts either that it is not yet time to philosophize, or that the hour is passed, is like a man who should say that the time is not yet come to be happy, or that it is too late. So that both young and old should study philosophy, the one in order that, when he is old, he many be young in good things through the pleasing recollection of the past, and the other in order that he may be at the same time both young and old, in consequence of his absence of fear for the future.
A happy and eternal being has no trouble himself and brings no trouble upon any other being; hence he is exempt from movements of anger and partiality, for every such movement implies weakness.
A happy and eternal being has no trouble himself and brings no trouble upon any other being; hence he is exempt from movements of anger and partiality, for every such movement implies weakness. (1)
What is blessed and indestructible has no troubles itself, nor does it give trouble to anyone else, so that it is not affected by feelings of anger or gratitude. For all such things are signs of weakness. (Hutchinson)
The blessed and immortal is itself free from trouble nor does it cause trouble for anyone else; therefore it is not constrained either by anger of favour. For such sentiments exist only in the weak (O'Connor)
A blessed and imperishable being neither has trouble itself nor does it cause trouble for anyone else; therefore, it does not experience anger nor gratitude, for such feelings signify weakness. (unsourced translation)
It is impossible to live a pleasantlife without living wisely and honorably and justly, and it is impossible to live wisely and honorably and justly without living pleasantly. Whenever any one of these is lacking, when, for instance, the man is not able to live wisely, though he lives honorably and justly, it is impossible for him to live a pleasant life. (5)
No pleasure is in itself evil, but the things which produce certain pleasures entail annoyances many times greater than the pleasures themselves. (8)
Variant translation: No pleasure is itself a bad thing, but the things that produce some kinds of pleasure, bring along with them unpleasantness that is much greater than the pleasure itself.
It is impossible for someone to dispel his fears about the most important matters if he doesn't know the nature of the universe but still gives some credence to myths. So without the study of nature there is no enjoyment of pure pleasure. (12)
Variant translation: One cannot rid himself of his primal fears if he does not understand the nature of the universe, but instead suspects the truth of some mythical story. So without the study of nature, there can be no enjoyment of pure pleasure. 
The wealth required by nature is limited and is easy to procure; but the wealth required by vain ideals extends to infinity. (15)
The flesh receives as unlimited the limits of pleasure; and to provide it requires unlimited time. But the mind, intellectually grasping what the end and limit of the flesh is, and banishing the terrors of the future, procures a complete and perfectlife, and we have no longer any need of unlimited time. Nevertheless the mind does not shun pleasure, and even when circumstances make death imminent, the mind does not lack enjoyment of the best life. (20)
Those who were best able to provide themselves with the means of security against their neighbors, being thus in possession of the surest guarantee, passed the most agreeable life in each other's society...
We must consider both the ultimate end and all clear sensory evidence, to which we refer our opinions; for otherwise everything will be full of uncertainty and confusion. (22)
If you reject absolutely any single sensation without stopping to discriminate with respect to that which awaits confirmation between matter of opinion and that which is already present, whether in sensation or in feelings or in any immediate perception of the mind, you will throw into confusion even the rest of your sensations by your groundless belief and so you will be rejecting the standard of truth altogether. If in your ideas based upon opinion you hastily affirm as true all that awaits confirmation as well as that which does not, you will not escape error, as you will be maintaining complete ambiguity whenever it is a case of judging between right and wrong opinion. (24)
Of our desires some are natural and necessary, others are natural but not necessary; and others are neither natural nor necessary, but are due to groundless opinion. (29)
Natural justice is a symbol or expression of usefulness, to prevent one person from harming or being harmed by another. (31)
Variant: Natural justice is a pledge of reciprocal benefit, to prevent one man from harming or being harmed by another.
Those animals which are incapable of making binding agreements with one another not to inflict nor suffer harm are without either justice or injustice; and likewise for those peoples who either could not or would not form binding agreements not to inflict nor suffer harm. (32)
It is impossible for a man who secretly violates the terms of the agreement not to harm or be harmed to feel confident that he will remain undiscovered, even if he has already escaped ten thousand times; for until his death he is never sure that he will not be detected. (35)
Among the things held to be just by law, whatever is proved to be of advantage in men's dealings has the stamp of justice, whether or not it be the same for all; but if a man makes a law and it does not prove to be mutually advantageous, then this is no longer just. And if what is mutually advantageous varies and only for a time corresponds to our concept of justice, nevertheless for that time it is just for those who do not trouble themselves about empty words, but look simply at the facts. (37)
Where without any change in circumstances the things held to be just by law are seen not to correspond with the concept of justice in actual practice, such laws are not really just; but wherever the laws have ceased to be advantageous because of a change in circumstances, in that case the laws were for that time just when they were advantageous for the mutual dealings of the citizens, and subsequently ceased to be just when they were no longer advantageous. (38)
Those who were best able to provide themselves with the means of security against their neighbors, being thus in possession of the surest guarantee, passed the most agreeable life in each other's society; and their enjoyment of the fullest intimacy was such that, if one of them died before his time, the survivors did not mourn his death as if it called for sympathy. (40)
Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God?
"God," he [Epicurus] says, "either wants to eliminate bad things and cannot,
or can but does not want to,
or neither wishes to nor can,
or both wants to and can.
If he wants to and cannot, then he is weak and this does not apply to god.
If he can but does not want to, then he is spiteful which is equally foreign to god's nature.
If he neither wants to nor can, he is both weak and spiteful, and so not a god.
If he wants to and can, which is the only thing fitting for a god, where then do bad things come from? Or why does he not eliminate them?"
Lactantius, On the Anger of God, 13.19
There has also arisen a further disputed extension, for which there has been found no published source prior to The Heretic's Handbook of Quotations: Cutting Comments on Burning Issues (1992) by Charles Bufe, p. 186: "Is he neither able nor willing? Then why call him God?"
For if they imagine infinite spaces of time before the world, during which God could not have been idle, in like manner they may conceive outside the world infinite realms of space, in which, if any one says that the Omnipotent cannot hold His hand from working, will it not follow that they must adopt Epicurus’ dream of innumerable worlds? with this difference only, that he asserts that they are formed and destroyed by the fortuitous movements of atoms, while they will hold that they are made by God’s hand, if they maintain that, throughout the boundless immensity of space, stretching interminably in every direction round the world, God cannot rest, and that the worlds which they suppose Him to make cannot be destroyed. ... there is no place beside the world ...no time before the world.