Even Shakespeare has been cited as being acquainted with the circulation of the blood, because he refers to its movement. This only illustrates the confusion which has often been made of movement with circulation. From the earliest times it had been believed there was movement of the blood, but there was no clear or correct idea as to the nature of the movement. The view may be ventured that another confusion is responsible for a good deal that has been said about Harvey having been forestalled in the discovery. It is confusing the passage through the lungs of _some_ blood with the _whole mass_ of it. It is difficult to believe, on taking a broad view of all their statements on the subject, that any of Harvey’s predecessors realised that the whole mass of the blood was continually passing through the lungs. Had they done so it is further difficult to see how the systemic circulation should have escaped them. But of this they certainly had no idea. We may admit all this previous knowledge without its detracting from the greatness and merit of Harvey’s work. Although the same anatomical facts, and even a glimmering of the Pulmonary Circulation may have been present to the minds of his predecessors or contemporaries, yet the genius, the spark of originality by which was discovered the proper relation to one another of the former, the true significance and meaning of the latter, belongs to Harvey and to him alone. As was said by one of the best informed minds[9] of the eighteenth century: “It is not to Cæsalpinus, because of some words of doubtful meaning, but to Harvey, the able writer, the laborious contriver of so many experiments, the staid propounder of all the arguments available in his day, that the immortal glory of having discovered the Circulation of the Blood is to be assigned.” [9] Haller, Elementa Physiologiæ, vol. i. lib. iii., 1757.