Even as wisdom often comes from the mouths of babes, so does it often come from the mouths of old people. The golden rule is to test everything in the light of reason and experience, no matter from where it comes.
Ultimate serenity is the coming to rest of all ways of taking things, the repose of named things; no truth has been taught by a Buddha for anyone, anywhere.
I have not professionally dealt in truth. Many when they come to die have spent all the truth that was in them, and enter the next world as paupers. I have saved up enough to make an astonishment there.
Nor seek, for this is also sooth,
To hunger fiercely after truth,
Lest all thy toiling only breeds
New dreams, new dreams; there is no truth
Saving in thine own heart.
By following this simple path, you become extraordinary, unfathomable, a being of profound cosmic subtlety. You outlive time and space by realizing the subtle truth of the universe.