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)

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)

They who retire themselves from the common offices, from that infinite number of troublesome rules that fetter a man of exact honesty in civil life, are in my opinion very discreet.

Montaigne

Montaigne on Death

But in dying, which is the greatest work we have to do, practice can give us no assistance at all.  A man may by custom fortify himself against pain, shame, necessity, and such-like accidents, but as to death, we can experiment it but once, and are all apprentices when we come to it.  There have, anciently, been men so excellent managers of their time that they have tried even in death itself to relish and taste it, and who have bent their utmost faculties of mind to discover what this passage is, but they are none of them come back to tell us the news....
 

Julius Canus, a noble Roman, of singular constancy and virtue, having been condemned to die by that worthless fellow Caligula, besides many marvellous testimonies that he gave of his resolution, as he was just going to receive the stroke of the executioner, was asked by a philosopher, a friend of his: “Well, Canus, whereabout is your soul now? what is she doing?  What are you thinking of?”--“I was thinking,” replied the other, “to keep myself ready, and the faculties of my mind full settled and fixed, to try if in this short and quick instant of death, I could perceive the motion of the soul when she parts from the body, and whether she has any sentiment at the separation, that I may after come again if I can, to acquaint my friends with it.” 

Michel de Montaigne

Ullrich told me about a small boy who was dying of neuroblastoma. “His mother made it very clear to him that she would see him again in Heaven someday. ... But he was worried about how he would find her. So they made a plan to meet in the front left corner of Heaven."

Jerome Groopman in The New Yorker, "Lives Less Ordinary" (January 20, 2014)

I plung'd for life or death. To interknit
One's senses with so dense a breathing stuff
Might seem a work of pain; so not enough
Can I admire how crystal-smooth it felt,
And buoyant round my limbs. At first I dwelt
Whole days and days in sheer astonishment;
Forgetful utterly of self-intent;
Moving but with the mighty ebb and flow.
Then, like a new fledg'd bird that first doth shew
His spreaded feathers to the morrow chill,
I tried in fear the pinions of my will.
'Twas freedom! and at once I visited
The ceaseless wonders of this ocean-bed.

Glaucus on entering the sea and breathing water, Keat's ENDYMION (line 380)