A man's most open actions have a secret side to them.

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.

Madness alone is truly terrifying, inasmuch as you cannot placate it by threats, persuasion, or bribes.

We penetrated deeper and deeper into the heart of darkness

Of all the inanimate objects, of all men's creations, books are the nearest to us for they contain our very thoughts, our ambitions, our indignations, our illusions, our fidelity to the truth, and our persistent leanings to error. But most of all they resemble us in their precious hold on life.

That faculty of beholding at a hint the face of his desire and the shape of his dream, without which the earth would know no lover and no adventurer.

You can't breathe dead hippo waking, sleeping, and eating, and at the same time keep your precarious grip on existence.