Ernst Cassirer, An Essay on Man: An Introduction to a Philosophy of Human Culture (1944):

That self-knowledge is the highest aim of philosophical inquiry appears to be generally acknowledged. In all the conflicts between the different philosophical schools this objective remained invariable and unshaken: it proved to be the Archimedean point, the fixed and immovable center, of all thought. Nor did the most sceptical thinkers deny the possibility and necessity of self-knowledge. They distrusted all general principles concerning the nature of things, but this distrust was only meant to open a new and more reliable mode of investigation.

Human beings have the capacity to courageously confront their suffering — to transcend it psychologically, as well as to ameliorate it practically. This is the most fundamental twin axiom of psychotherapy, regardless of school of thought, as well as key to the mystery of human success and progress across history itself.