A book published in 1946 is "very old"?! hehe. Maybe try Plutarch's
Lives (about 100AD), or Xenophon's
Memorabilia of Socrates (about 370BC), both of which are extremely readable, gossipy even, and touch on that subject. Marvel at how little's changed.
If I had to name one book, I guess Emerson's Essays: First and Second Series, (that first copy I had also included Representative Men) which I discovered when I was about 20, and read from almost every day for at least 10 years, and still never go more than a few days without....well, it's more myself than I am (to paraphrase Emerson, I think). Trying to track that quote down just now, I realized that Emerson's Uses of Great Men[0] explains the matter far better than I could.
The first time I read it, it was like he'd described 10,000 things I'd experienced, and had thought couldn't possibly be described. That was 27 years ago. I can't imagine at all what difference not coming across him would have made, but I guess "it actually changed my life" would be a huge understatement. Also Russell, Hazlitt, Chesterton, Santayana, Stevenson, William James, Nietzsche etc have been hugely important, but....somehow, in various ways, none are quite such admirable characters, or teachers for all seasons.[1] This:
"It is nothing for any man sitting in his chair to be overcome with the sense of the immediacy of life, to feel the spur of courage, the victory of good over evil, the value, now and forever, of all great-hearted endeavor. Such moments come to us all. But for a man to sit in his chair and write what shall call up these forces in the bosoms of others – that is desert, that is greatness. To do this was the gift of Emerson. The whole earth is enriched by every moment of converse with him. The shows and shams of life become transparent, the lost kingdoms are brought back, the shutters of the spirit are opened, and provinces and realms of our own existence lie gleaming before us." – JJ Chapman
[0]https://en.wikisource.org/wiki/Representative_Men/Uses_of_Gr...
[1] I almost added Thoreau, but he seems an extension of Emerson, unimaginable without him. Well, you could say that about Nietzsche too.
"Emerson. – Never have I felt so much at home in a book, and in my home, as – I may not praise it, it is too close to me." – Nietzsche