The illustrative plates to which Diderot gave the most laborious attention for a period of almost thirty years, are not only remarkable for their copiousness, their clearness, their finish—­and in all these respects they are truly admirable—­but they strike us even more by the semi-poetic feeling that transforms the mere representation of a process into an animated scene of human life, stirring the sympathy and touching the imagination of the onlooker as by something dramatic.  The bustle, the dexterity, the alert force of the iron foundry, the glass furnace, the gunpowder mill, the silk calendry are as skilfully reproduced as the more tranquil toil of the dairywoman, the embroiderer, the confectioner, the setter of types, the compounder of drugs, the chaser of metals.  The drawings recall that eager and personal interest in his work, that nimble complacency, which is so charming a trait in the best French craftsman.  The animation of these great folios of plates is prodigious.  They affect one like looking down on the world of Paris from the heights of Montmartre.  To turn over volume after volume is like watching a splendid panorama of all the busy life of the time.  Minute care is as striking in them as their comprehensiveness.  The smallest tool, the knot in a thread, the ply in a cord, the curve of wrist or finger, each has special and proper delineation.  The reader smiles at a complete and elaborate set of tailor’s patterns.  He shudders as he comes upon the knives, the probes, the bandages, the posture, of the wretch about to undergo the most dangerous operation in surgery.  In all the chief departments of industry there are plates good enough to serve for practical specifications and working drawings.  It has often been told how Diderot himself used to visit the workshops, to watch the men at work, to put a thousand questions, to sit down at the loom, to have the machine pulled to pieces and set together again before his eyes, to slave like any apprentice, and to do bad work, in order, as he says, to be able to instruct others how to do good work.  That was no movement of empty rhetoric which made him cry out for the Encyclopaedia to become a sanctuary in which human knowledge might find shelter against time and revolutions.  He actually took the pains to make it a complete storehouse of the arts, so perfect in detail that they could be at once reconstructed after a deluge in which everything had perished save a single copy of the Encyclopaedia.  Such details, said D’Alembert, will perhaps seem extremely out of place to certain scholars, for whom a long dissertation on the cookery or the hair-dressing of the ancients, or on the site of a ruined hamlet, or on the baptismal name of some obscure writer of the tenth century, would be vastly interesting and precious.  He suggests that details of economy, and of arts and trades, have as good a right to a place as the scholastic philosophy, or some system of rhetoric still in use, or the mysteries of heraldry.  Yet none even of these had been passed over.[168]