The way I view the whole acceptance and/or approval thing is as follows:
At any given point in time, a particular person might be considered the greatest to exist in their field—think of figures like Galileo, Euclid, Newton, Leibniz, Euler, Einstein, Feynman, etc. As someone starting out in the field, I would aspire to achieve the recognition that such a person had in their time period. But if I were to reach that level of greatness, would I be satisfied? How could I know if I am the greatest of my time period or of all time periods? There isn’t a reliable measure to compare the contributions of Newton and Einstein. Who do we label as the genius of geniuses? If we were to swap their eras, would Einstein have discovered the theory of gravitation like Newton did? Would he have sat under the same tree? Would Newton, if he lived in the early 1900s instead, have been able to develop the theory of relativity given the pre-existing theory of gravitation?
We cannot know if these individuals, placed in different times, would achieve the same accomplishments. Since the answer is likely no, one should not focus too much on acceptance or approval since what is considered art is one era might not in another. As the book mentions, the reward for recognition might arrive later, or even, never. Thus, focusing too much on acceptance hinders creation. Copernicus was a madman then when he proposed a heliocentric solar system model. Today, he is a man of science. Had he been too focused on acceptance, Earth would still have been the center of the universe. A bit pompous of us should I say. Therefore, what we can strive for is the goal to become better than we were a moment ago (a cliché, yes, but important nonetheless) because that is actually measurable.