All ambitions are lawful except those which climb upward on the miseries or credulities of mankind. All intellectual and artistic ambitions are permissible, up to and even beyond the limit of prudent sanity. They can hurt no one.
It is when we try to grapple with another man's intimate need that we perceive how incomprehensible, wavering, and misty are the beings that share with us the sight of the stars and the warmth of the sun.
Some great men owe most of their greatness to the ability of detecting in those they destine for their tools the exact quality of strength that matters for their work.