W. Somerset Maugham said this quote

... I was perturbed by the suspicion that the anguish of love contemned was alloyed in her broken heart with the pangs, sordid in my young mind, of wounded vanity. I had not yet learnt how contradictory is human nature; I did not know how much pose there is in the sincere. how much baseness in the noble, nor how much goodness in the reprobate.