He who knows not what the Universe is knows not what is his place therein. He who knows not for what end it was created, knows not himself and knows not the world. He who is deficient in either of these parts of knowledge cannot even say for what end he himself was created.

 Marcus Aurelius, Meditations (VIII,52)

A man's worth is just the worth of that which he pursues....Be upright either by nature or by correction.

Contemplate the courses of the stars, as one should do that revolves along with them. Consider also without ceasing the changes of elements, one into another. Speculations upon such things cleanse away the filth of this earthly life.

Marcus Aurelius, Meditations (Book 7)

Consider frequently how swiftly things that exist or are coming into existence are swept by and carried away. Their substance is as a river perpetually flowing; their actions are in continual change, and their causes subject to ten thousand alterations. Scarcely anything is stable, and the vast eternities of past and future in which all things are swallowed up are close upon us on both hands. Is he not then a fool who is puffed up with success in the things of this world, or is distracted, or worried, as if he were in a time of trouble likely to endure for long.


Marcus Aurelius, Meditations  (V,23)

Man must consider, not only that each day part of his life is spent, and that less and less remains to him, but also that, even if he live longer, it is very uncertain whether his intelligence will suffice as heretofore for the understanding of his affairs, and for grasping that knowledge which aims at comprehending things human and divine. When dotage begins, breath, nourishment, fancy, impulse, and so forth will not fail him. But self-command, accurate appreciation of duty, power to scrutinize what strikes his senses, or even to decide whether he should take his departure, all powers, indeed, which demand a well-trained understanding, must be extinguished in him. Let him be up and doing then, not only because death comes nearer every day, but because understanding and intelligence often leave us before we die. 

Marcus Aurelius, Meditations  (III,1)