Trying to write something of permanent value is a full-time job even though only a few hours a day are spent on the actual writing. A writer can be compared to a well. There are as many kinds of wells as there are writers. The important thing is to have good water in the well, and it is better to take a regular amount out than to pump the well dry and wait for it to refill.
–E. Hemingway, as told to George Plimpton, Spring 1958, the Paris Review