Speaking of his admiration for the great French dramatists, Dugald Stewart states that "this admiration (resulting originally from the general character of his taste, which delighted more to remark that pliancy of genius which accommodates itself to general rules than to wonder at the bolder flights of an undisciplined imagination) was increased to a great degree when he saw the beauties that had struck him in the closet heightened by the utmost perfection of theatrical exhibition."[176] The French theatre, indeed, gave him much material for reflection. In his later years his thoughts and his conversation often recurred to the philosophy of the imitative arts. He meant had he lived to have written a book on the subject; he has actually left us a single essay, one of the most finished pieces of work he ever did; and among his friends he was very fond in those days of speaking and theorising on that topic, and supporting his conclusions by illustrations from his wide reading and his observation of life. These illustrations seem to have been drawn frequently from his experiences of the French theatre. The Earl of Buchan says that Smith had no ear for music, but there are few things he seems to have nevertheless enjoyed better than the opera, both serious and comic. He thought the "sprightly airs" of the comic opera, though a more "temperate joy" than "the scenes of the common comedy," were still a "most delicious" one.'[177] "They do not make us laugh so loud, but they make us smile more frequently." And he held the strongest opinion that music was always on virtue's side, for he says the only musical passions are the good ones, the bad and unsocial passions being, in his view, essentially unmelodious. But he thought scenery was much abused on the French operatic stage. "In the French operas not only thunder and lightning, storms and tempests, are commonly represented in the ridiculous manner above mentioned, but all the marvellous, all the supernatural of epic poetry, all the metamorphoses of mythology, all the wonders of witchcraft and magic, everything that is most unfit to be represented upon the stage, are every day exhibited with the most complete approbation and applause of that ingenious nation."[178]