"Trouble has no necessary connection with discouragement. Discouragement has a germ of its own, as different from trouble as arthritis is different from a stiff joint"

This quote by F. Scott Fitzgerald is stressing the idea that difficulty and frustration are two different entities. Problem is an external force that can be dealt with and overcome, while frustration is an internal feeling that can be more difficult to conquer. Fitzgerald is comparing the two by comparing problem to a stiff joint, which can be dealt with and healed, and discouragement to arthritis, which is a chronic condition that can be handled but not treated. He is recommending that while difficulty can be dealt with and dominated, discouragement is a more complicated problem that needs more effort to overcome. This quote is a pointer that while difficulty can be tough, it is not always connected to discouragement, which discouragement is a distinct obstacle that needs its own set of techniques to get rid of.