Montesquieu used to declare that he had never known a chagrin which half an hour of a book was not able to dispel.  Diderot had the same fortunate temper.

Yet Diderot was not essentially a man of books.  He never fell into the characteristic weakness of the follower of letters, by treating books as ends in themselves, or placing literature before life.  Character, passion, circumstance, the real tragi-comedy, not its printed shadow and image, engrossed him.  He was in this respect more of the temper of Rousseau, than he was like Voltaire or Fontenelle.  “Abstraction made,” he used to say, “of my existence and of the happiness of my fellows, what does the rest of nature matter to me?” Yet, as we see, nobody that ever lived was more interested in knowledge.  His biographer and disciple remarked the contrast in him between his ardent impetuous disposition and enthusiasm, and his spirit of close unwearied observation. Faire le bien, connaitre le vrai, was his formula for the perfect life, and defined the only distinction that he cared to recognise between one man and another.  And the only motive he ever admitted as reasonable for seeking truth, was as a means of doing good.  So strong was his sense of practical life, in the midst of incessant theorising.

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At the moment when he had most difficulty in procuring a little bread each day for himself, Diderot conceived a violent passion for a seamstress, Antoinnette Champion by name, who happened to live in his neighbourhood.  He instantly became importunate for marriage.  The mother long protested with prudent vigour against a young man of such headstrong impetuosity, who did nothing and who had nothing, save the art of making speeches that turned her daughter’s head.  At length the young man’s golden tongue won the mother as it had won the daughter.  It was agreed that his wishes should be crowned, if he could procure the consent of his family.  Diderot fared eagerly and with a sanguine heart to Langres.  His father supposed that he had seen the evil of his ways, and was come at last to continue the honest tradition of their name.  When the son disclosed the object of his visit, he was treated as a madman and threatened with malediction.  Without a word of remonstrance he started back one day for Paris.  Madame Champion warned him that his project must now be for ever at an end.  Such unflinching resoluteness is often the last preliminary before surrender.  Diderot fell ill.  The two women could not bear to think of him lying sick in a room no better than a dog-kennel, without broths and tisanes, lonely and sorrowful.  They hastened to nurse him, and when he got well, what he thought the great object of his life was reached.  He and his adored were married (1743).[16] As has been said, “Choice in marriage is a great match of cajolery between purpose and invisible hazard:  deep criticism of a game of pure chance is time wasted.”  In Diderot’s case destiny was hostile.