The mother: “Honey, what’s that smell coming from the basement?”
The father: “Well, I don’t know, hon, let me take a whiff. Why, that’s nitric acid from drain cleaner, sulphuric acid from rust remover, with a soupçon of acetone from nail polish remover.

So, what did Diderot mean by calling his thoughts harlots? That his thoughts were immoral? That his notions were wicked? That his ideas were depraved? That his dissolute mind was spewing forth figments of shameful introspection, or meditation that was wanton and promiscuous? If you think like this, you must be a speaker of English.