Some noteworthy maxims from the Doctor’s 1759 pilgrimage novel The History of Rasselas, The Prince of Abissinia:

Every man may, by examining his own mind, guess what passes in the minds of others.

Truth, such as is necessary to the regulation of life, is always found where it is honestly sought.

I have, said the princess, enabled myself to enter familiarly into many families, where there was the fairest show of prosperity and peace, and know not one house that is not haunted by some fury that destroys its quiet.

The truth is, that no mind is much employed upon the present: recollection and anticipation fill up almost all our moments.

No disease of the imagination, answered Imlac [Imlac's is the voice of Samuel Johnson], is so difficult of cure, as that which is complicated with the dread of guilt.  … If fancy presents images not moral or religious, the mind drives them away when they give it pain, but when melancholick [i.e., depressed] notions take the form of duty, they lay hold on the faculties without opposition.