I found this letter uploaded here, after it was referenced in a ceremony by Justice Stanley Mosk’s son, honoring the late Justice. I wrote about more quotes from that ceremony here.

My dear Paul:

No one can be a truly competent lawyer unless he is a cultivated man. If I were you, I would forget about any technical preparation for the law. The best way to prepare for the law is to be a well-read person.

Thus, alone can one acquire the capacity to use the English language on paper and in speech and with the habits of clear thinking that, only a truly liberal education can give. No less important for a lawyer is the cultivation of the imaginative faculties by reading poetry, seeing great paintings, in the original or in easily available reproductions, and listening to great music. Stock your mind with the deposit of much good reading, widen and deepen your feelings by experiencing vicariously as much as possible the wonderful mysteries of the universe, and forget about your future career. With good wishes,

Sincerely yours,

[Signed] Felix Frankfurter

M. Paul Claussen, Jr