My favourite is the following from author Fyodor Dostoevsky on epileptically induced ecstasy:
“There are moments, and it is only a matter of five or six seconds, when you feel the presence of the eternal harmony…a terrible thing is the frightful clearness with which it manifests itself and the rapture with which it fills you. If this state were to last more than five seconds, the soul could not endure it and would have to disappear. During these five seconds I live a whole human existence, and for that I would give my whole life and not think that I was paying too dearly….”
Link to ‘On The Nature of Experience’.