The scope of the Philosophical Thoughts, and the attitude of Diderot’s mind when they were written, may be shown in a few brief passages.  The opening words point to the significance of the new time in one direction, and they are the key-note to Diderot’s whole character.  “People are for ever declaiming against the passions; they set down to them all the pains that man endures, and quite forget that they are also the source of all his pleasures.  It is regarded as an affront to reason if one dares to say a word in favour of its rivals.  Yet it is only passions, and strong passions, that can raise the soul to great things.  Sober passions produce only the commonplace.  Deadened passions degrade men of extraordinary quality.  Constraint annihilates the greatness and energy of nature.  See that tree; ’tis to the luxury of its branches that you owe the freshness and the wide-spreading breadth of its shade, which you may enjoy till winter comes to despoil it of its leafy tresses.  An end to all excellence in poetry, in painting, in music, as soon as superstition has once wrought upon human temperament the effect of old age!  It is the very climax of madness to propose to oneself the ruin of the passions.  A fine design truly in your pietist, to torment himself like a convict in order to desire nothing, love nothing, feel nothing; and he would end by becoming a true monster, if he were to succeed!"[34] Many years afterwards he wrote in the same sense to Madame Voland.  “I have ever been the apologist of strong passions; they alone move me.  Whether they inspire me with admiration or horror, I feel vehemently.  If atrocious deeds that dishonour our nature are due to them, it is by them also that we are borne to the marvellous endeavour that elevates it.  The man of mediocre passion lives and dies like the brute.”  And so forth, until the writer is carried to the perplexing position that “if we were bound to choose between Racine, a bad husband, a bad father, a false friend, and a sublime poet, and Racine, good father, good husband, good friend, and dull worthy man, I hold to the first.  Of Racine, the bad man, what remains?  Nothing.  Of Racine, the man of genius?  The work is eternal."[35] Without attempting to solve this problem in casuistry, we recognise Diderot’s mood, and the hatred with which it would be sure to inspire him for the starved and mutilated passions of the Christian type.  The humility, chastity, obedience, indolent solitude, which had for centuries been glorified by the Church, were monstrous to this vehement and energetic spirit.  The church had placed heroism in effacement.  Diderot, borne to the other extreme, left out even discipline.  To turn from his maxims on the foundation of conduct, to his maxims on opinion.  As we have said, his attitude is that of the sceptic:—­

What has never been put in question, has not been proved.  What people have not examined without prepossessions, they have not examined thoroughly.  Scepticism is the touchstone. (Sec. 31.)