From "Art and Fear," by David Bayles and Ted Orland, 1993:
Given a small kernel of reality and any measure of optimism, nebulous expectations whisper to you that the work will soar, that it will become easy, that it will make itself. And verily, now and then the sky opens and the work does make itself. Unreal expectations are easy to come by, both from emotional needs and from the hope or memory of periods of wonder. Unfortunately, expectations based on illusion lead almost always to disillusionment.
Conversely, expectations based on the work itself are the most useful tool the artist possesses. What you need to know about the next piece is contained in the last piece. The place to learn about your materials is in the last use of your materials. The place to learn about your execution is in your execution. The best information about what you love is in your last contact with what you love. Put simply, your work is your guide: a complete, comprehensive, limitless reference book on your work. There is no other such book, and it is yours alone. It functions this way for no one else. Your fingerprints are all over your work, and you alone know how they got there. Your work tells you about your working methods, your discipline, your strengths and weaknesses, your habitual gestures, your willingness to embrace.
The lessons you are meant to learn are in your work. To see them, you need only look at the work clearly -- without judgement, without need or fear, without wishes or hopes. Without emotional expectations. Ask your work what it needs, not what you need.