The Madonna, of course, is the extreme example; but there are dozens of “The Last Supper,” “Abraham’s Sacrifice,” “The Final Judgment,” “The Brazen Serpent,” “Raising of Lazarus,” “The Annunciation,” “Rebekah at the Well” and so on.

If one painter produced a notable picture, all the other artists in the vicinity felt it their duty to treat the same subject; in fact, their honor was at stake—­they just had to, in order to satisfy the clamor of their friends, and meet the challenges of detractors.

This “progressive sketching” was kept up, each man improving, or trying to improve, on the attempts of the former, until a Leonardo struck twelve and painted his “Last Supper,” or a Rubens did his “Descent From the Cross”—­then competitors grew pale, and tried their talent on a lesser theme.

One of the most curious examples of the tendency to follow a bellwether is found in the various pictures called “The Anatomy Lesson.”  When Venice was at its height, in the year Fourteen Hundred Ninety-two—­a date we can easily remember—­an unknown individual drew a picture of a professor of anatomy; on a table in the center is a naked human corpse, while all around are ranged the great doctor’s pupils.  Dissection had just been introduced into Venice at that time, and in a treatise on the subject by Andrea Vesali, I find that it became quite the fad.  The lecture-rooms were open to the public, and places were set apart for women visitors and the nobility, while all around the back were benches for the plain people.  On the walls were skeletons, and in cases were arranged saws, scalpels, needles, sponges and various other implements connected with the cheerful art.

The Unknown’s picture of this scene made a sensation.  And straightway other painters tried their hands at it, the unclothed form of the corpse affording a fine opportunity for the “classic touch.”  Paul Veronese tried it, and so did the Bellinis—­Titian also.

Then a century passed, as centuries do, and the glory of Venice drifted to Amsterdam—­commercially and artistically.  Amsterdam painters used every design that the Venetians had, and some of their efforts were sorry attempts.  In Sixteen Hundred Twenty, following Venetian precedent, dissection became a fad in Leyden and Amsterdam.  Swanenburch engraved a picture of the Leyden dissecting-room, with a brace of gallant doctors showing some fair ladies the beauties of the place.  The Dutch were ambitious—­the young men, Rembrandt included, drew pictures entitled, “The Lesson in Anatomy.”  Doctors who were getting on in the world gave orders for portraits, showing themselves as about to begin work on a subject.  One physician, with intent to get even with his rival, had the artist picture the rival in the background as a pupil.  Then the rival ordered a picture of himself, proud and beautiful, giving a lesson in anatomy, armed and equipped for business, and the cadaver was—­the other doctor.