To quote the psychotherapist Alfred Adler:
"We should not be astonished if in the cases where we see an inferiority [feeling] complex we find a superiority complex more or less hidden. On the other hand, if we inquire into a superiority complex and study its continuity, we can always find a more or less hidden inferiority [feeling] complex."
"If a person is a show-off it is only because he feels inferior, because he does not feel strong enough to compete with others on the useful side of life. That is why he stays on the useless side. He is not in harmony with society. It seems to be a trait of human nature that when individuals - both children and adults - feel weak, they want to solve the problems of life in such a way as to obtain personal superiority without any admixture of social interest. A superiority complex is a second phase. It is a compensation for the inferiority [feeling] complex."
"The superiority complex is one of the ways which a person with an inferiority [feeling] complex may use as a method of escape from his difficulties. He assumes that he is superior when he is not, and this false success compensates him for the state of inferiority which he cannot bear. The normal person does not have a superiority complex, he does not even have a sense of superiority. He has the striving to be superior in the sense that we all have ambition to be successful; but so long as this striving is expressed in work it does not lead to false valuations, which are at the root of mental disease".