As there must be moderation in other things, so there must be moderation in self-criticism. Perpetual contemplation of our own actions produces a morbid consciousness, quite unlike that normal consciousness accompanying right actions spontaneously done; and from a state of unstable equilibrium long maintained by effort, there is apt to be a fall towards stable equilibrium, in which the primitive nature reasserts itself. Retrogression rather than progression may hence result.
Ch. 10, General Conclusions. - The Principles of Ethics, Vol. I (1897) - Part III: The Ethics of Individual Life