The Enchiridion, by Epictetus: V

Men are disturbed not by the things which happen, but by the opinions about the things: for example, death is nothing terrible, for if it were, it would have seemed so to Socrates; for the opinion about death, that it is terrible, is the terrible thing. When then, we are impeded or dis­turbed or grieved, let us never blame others, but ourselves, that is, our opinions. It is the act of an ill-instructed man to blame others for his own bad condition; it is the act of one who has begun to be instructed, to lay the blame on himself; and of one whose instruction is completed, neither to blame another, nor himself.

The Enchiridion, by Epictetus: IV

When you are going to take in hand any act, remind yourself what kind of an act it is. If you are going to bathe, place before yourself what happens in the bath: some splashing the water, others pushing against one another, others abusing one another, and some stealing: and thus with more safety you will undertake the matter, if you say to yourself, I now intend to bathe, and to maintain my will in a manner con­formable to nature. And so you will do in every act: for thus if any hindrance to bathing shall happen, let this thought be ready; it was not this only that I intended, but I intended also to maintain my will in a way conformable to nature; but I shall not maintain it so, if I am vexed at what happens.

The Enchiridion, by Epictetus: III

In everything which pleases the soul, or supplies a want, or is loved, remember to add this to the (description, notion): What is the nature of each thing, beginning from the smallest? If you love an earthen vessel, say it is an earthen vessel which you love; for when it has been broken, you will not be disturbed. If you are kissing your child or wife, say that it is a human being whom you are kissing, for when the wife or child dies, you will not be disturbed.

The Enchiridion, by Epictetus: II

Remember that desire contains in it the profession (hope) of obtaining that which you desire; and the profession (hope) in aversion (turning from a thing) is that you will not fall into that which you attempt to avoid: and he who fails in his desire is unfortunate; and he who falls into that which he would avoid, is unhappy. If then you attempt to avoid only the things contrary to nature which are within your power, you will not be involved in any of the things which you would avoid. But if you attempt to avoid disease or death or poverty, you will be unhappy.

Take away, then, aversion from all things which are not in our power, and transfer it to the things contrary to nature which are in our power. But destroy desire completely for the present. For if you desire anything which is not in our power, you must be unfortunate: but of the things in our power, and which it would be good to desire, nothing yet is before you. But employ only the power of moving toward an object and retiring from it; and these powers indeed only slightly and with exceptions and with remission.

The Enchiridion, by Epictetus: I

Of things some are in our power, and others are not. In our power are opinion, movement toward a thing, desire, aversion (turning from a thing); and in a word, whatever are our own acts: not in our power are the body, property, reputation, offices (magisterial power), and in a word, what­ever are not our own acts. And the things in our power are by nature free, not subject to restraint nor hindrance: but the things not in our power are weak, slavish, subject to restraint, in the power of others.

Remember then that if you think the things which are by nature slavish to be free, and the things which are in the power of others to be your own, you will be hindered, you will lament, you will be disturbed, you will blame both gods and men: but if you think that only which is your own to be your own, and if you think that what is another’s, as it really is, belongs to another, no man will ever compel you, no man will hinder you, you will never blame any man, you will accuse no man, you will do nothing involuntarily (against your will), no man will harm you, you will have no enemy, for you will not suffer any harm.

If then you desire (aim at) such great things, remember that you must not (attempt to) lay hold of them with a small effort; but you must leave alone some things entirely, and postpone others for the present. But if you wish for these things also (such great things), and power (office) and wealth, perhaps you will not gain even these very things (power and wealth) because you aim also at those former things (such great things): certainly you will fail in those things through which alone happiness and freedom are secured. Straightway, then, practice saying to every harsh appearance, You are an appearance, and in no manner what you appear to be. Then examine it by the rules which you possess, and by this first and chiefly, whether it relates to the things which are in our power or to the things which are not in our power: and if it relates to anything which is not in our power, be ready to say, that it does not con­cern you.

Theodore Roosevelt’s “Man in the Arena”

From “Citizenship in a Republic”.

It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat.

“Of a Happy Life” by Seneca

What answer are we to make to the reflexion that pleasure belongs to good and bad men alike, and that bad men take as much delight in their shame as good men in noble things? This was why the ancients bade us lead the highest, not the most pleasant life, in order that pleasure might not be the guide but the companion of a right-thinking and honourable mind; for it is Nature whom we ought to make our guide: let our reason watch her, and be advised by her. To live happily, then, is the same thing as to live according to Nature: what this may be, I will explain.

If we guard the endowments of the body and the advantages of nature with care and fearlessness, as things soon to depart and given to us only for a day; if we do not fall under their dominion, nor allow ourselves to become the slaves of what is no part of our own being; if we assign to all bodily pleasures and external delights the same position which is held by auxiliaries and light-armed troops in a camp; if we make them our servants, not our masters—then and then only are they of value to our minds.

A man should be unbiased and not to be conquered by external things: he ought to admire himself alone, to feel confidence in his own spirit, and so to order his life as to be ready alike for good or for bad fortune. Let not his confidence be without knowledge, nor his knowledge without steadfastness: let him always abide by what he has once determined, and let there be no erasure in his doctrines.

It will be understood, even though I append it not, that such a man will be tranquil and composed in his demeanour, high-minded and courteous in his actions. Let reason be encouraged by the senses to seek for the truth, and draw its first principles from thence: indeed it has no other base of operations or place from which to start in pursuit of truth: it must fall back upon itself. Even the all-embracing universe and God who is its guide extends himself forth into outward things, and yet altogether returns from all sides back to himself. Let our mind do the same thing: when, following its bodily senses it has by means of them sent itself forth into the things of the outward world, let it remain still their master and its own.

By this means we shall obtain a strength and an ability which are united and allied together, and shall derive from it that reason which never halts between two opinions, nor is dull in forming its perceptions, beliefs, or convictions. Such a mind, when it has ranged itself in order, made its various parts agree together, and, if I may so express myself, harmonized them, has attained to the highest good: for it has nothing evil or hazardous remaining, nothing to shake it or make it stumble: it will do everything under the guidance of its own will, and nothing unexpected will befall it, but whatever may be done by it will turn out well, and that, too, readily and easily, without the doer having recourse to any underhand devices: for slow and hesitating action are the signs of discord and want of settled purpose.

You may, then, boldly declare that the highest good is singleness of mind: for where agreement and unity are, there must the virtues be: it is the vices that are at war one with another.