Spinoza: A Life

"after experience had taught me that all the things which regularly
occur in ordinary life are empty and futile, and I saw that all the
things which were the cause or object of my fear had nothing of good
or bad in themselves, except insofar as (my) mind was moved
by them, I resolved at last to try to find out whether there was
anything which would be true good, capable of communicating itself,
and which alone would affect the mind, all others being rejected
-whether there was something which, once found and acquired,
would continuously give me the greatest joy, to eternity"

Treatise on the Emendation of the Intellect, II/5; C/7.