Book knowledge is valuable, but the knowledge which comes from mind intercourse is invaluable.
Two substances totally unlike, but having a chemical affinity for each other, may produce a third infinitely stronger than either, or even both of those which unite.

Two people with a strong affinity often call into activity in each other a power which neither dreamed he possessed before.

Many an author owes his greatest book, his cleverest saying to a friend who has aroused in him latent powers which otherwise might have remained dormant.

Artists have been touched by the power of inspiration through a masterpiece, or by some one they happened to meet who saw in them what no one else had ever seen,--the power to do an immortal thing.
The man who mixes with his fellows is ever on a voyage of discovery, finding new islands of power in himself which would have remained forever hidden but for association with others.

Everybody he meets has some secret for him, if he can only extract it, something which he never knew before, something which will help him on his way, something which will enrich his life.