Although from the beginning
I knew
the world is impermanent,
not a moment passes
when my sleeves are dry.
~ Ryokan
When you are delighted with anything, be delighted as with a thing which is not one of those which cannot be taken away, but as something of such a kind, as an earthen pot is, or a glass cup, that, when it has been broken, you may remember what it was and may not be troubled… What you love is nothing of your own: it has been given to you for the present, not that it should not be taken from you, nor has it been given to you for all time, but as a fig is given to you or a bunch of grapes at the appointed season of the year. But if you wish for these things in winter, you are a fool. So if you wish for your son or friend when it is not allowed to you, you must know that you are wishing for a fig in winter.
At the times when you are delighted with a thing, place before yourself the contrary appearances.
~ Epictetus
from The Discourses of Epictetus
with thanks to brainpickings