Marcus Aurelius wrote the Meditations in tents and border camps, on campaign along the Danube, in a period when a plague brought back from the East was moving through the legions and the city both. He was not a man reflecting on mortality from a safe distance. Book 2, written near the beginning of the notebook, opens with a passage that reads less like philosophy than like a note pinned above a desk:
Even if you were destined to live three thousand years, or thirty thousand, remember that no one loses any life other than the one he lives, and lives no other life than the one he loses. The longest and the shortest amount to the same thing.
The arithmetic is deliberately unsettling. A person does not have a stock of years sitting in reserve, some to spend now and some to save. There is only the present stretch of time, and that is the entire holding. Marcus draws a plain conclusion from this: the habit of postponing a full life until some future arrangement of circumstances — more security, more leisure, more resolved conditions — rests on a mistaken picture of what a life actually is. There is no later reservoir to draw down. There is only what is happening now, being lived or not being lived.
Henry David Thoreau reached a nearly identical conclusion by a different route. In Walden, in the chapter called "Where I Lived, and What I Lived For," he explains why he built a cabin at the pond and moved into it: "I wanted to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived." The word doing the work there is deliberately — not spontaneously, not accidentally, but as a chosen act repeated daily. Thoreau stripped his possessions and his obligations down to almost nothing not because scarcity was virtuous in itself, but because he suspected that most of what people accumulate is a kind of elaborate excuse for not yet beginning to live.
Both men are describing the same failure from opposite ends. Marcus watches people treat the present as a rehearsal, something to be gotten through on the way to a better-provisioned future. Thoreau watches people build that future so elaborately — the house, the furniture, the farm, the debts required to hold it all — that the building consumes the very life it was meant to prepare for. In each case, the deferred life turns out to be the only life on offer, spent in preparation for a performance that never opens.
Nothing here asks for austerity or an early death to concentrate the mind. It asks only for arithmetic done honestly: today is not a down payment on a fuller life to come. It is the whole of the transaction, receipt included.