These propositions Harvey proves to demonstration and in a most masterly manner. He says of the first: "Let us assume either arbitrarily or by experiment, that the quantity of the blood which the left ventricle of the heart will contain when distended to be, say two ounces, three ounces, or one ounce and a half--in the dead body I have found it to hold upwards of two ounces. Let us assume further how much less the heart will hold in the contracted than in the dilated state, and how much blood it will project into the aorta upon each contraction, and all the world allows that with the systole something is always projected ... and let us suppose as approaching the truth that the fourth, or fifth, or sixth, or even but the eighth part of its charge is thrown into the artery at each contraction, this would give either half an ounce, or three drachms, or one drachm of blood as propelled by the heart at each pulse into the aorta, which quantity by reason of the valves at the root of the vessel can by no means return into the ventricle. Now in the course of half an hour the heart will have made more than one thousand beats, in some as many as two, three, or even four thousand. Multiplying the number of drachms by the number of pulses we shall have either one thousand half ounces, or one thousand times three drachms, or a like proportional quantity of blood, according to the amount we assume as propelled with each stroke of the heart, sent from this organ into the artery: a larger quantity in every case than is contained in the whole body. In the same way in the sheep or dog, say that but a single scruple of blood passes with each stroke of the heart, in one half hour we should have one thousand scruples, or about three pounds and a half of blood injected into the aorta, but the body of neither animal contains more than four pounds of blood, a fact which I have myself ascertained in the case of the sheep." This is one of the highest efforts of Harvey's genius. The facts are simple and they are easily ascertained. But the reasoning was absolutely new and the conclusion must remain sound until the end of time, for it is true. It shows too the minute care taken by Harvey not to overstate his case, for he deliberately takes a measurement of the capacity of the ventricles which he knew to be well under the average.