Horace

   Ask not ('tis forbidden knowledge), what our destined term of years,
   Mine and yours; nor scan the tables of your Babylonish seers.
   Better far to bear the future, my Leuconoe, like the past,
   Whether Jove has many winters yet to give, or this our last;
   THIS, that makes the Tyrrhene billows spend their strength against
        the shore.
   Strain your wine and prove your wisdom; life is short; should hope
        be more?
   In the moment of our talking, envious time has ebb'd away.
   Seize the present; trust to-morrow e'en as little as you may.

-Horace Odes

Raymond Carver - The Cobweb

A few minutes ago, I stepped onto the deck
of the house. From there I could see and hear the water,
and everything that's happened to me all these years.
It was hot and still. The tide was out.
No birds sang. As I leaned against the railing
a cobweb touched my forehead.
It caught in my hair. No one can blame me that I turned
and went inside. There was no wind. The sea
was dead calm. I hung the cobweb from the lampshade.
Where I watch it shudder now and then when my breath
touches it. A fine thread. Intricate.
Before long, before anyone realizes,
I'll be gone from here.

opportunity cost

Still my favorite concept from economics.