Capello seized upon it, and repeated it two and a half years later, stating on September 28, 1500: "etiam amazo il fratello." And there you have the whole source of all the unbridled accusations subsequently launched against Cesare, all of which find a prominent place in Gregorovius's Geschichte der Stadt Rom, whilst the rumours accusing others, which we have mentioned here, are there slurred over.
One hesitates to attack the arguments and conclusions of the very eminent author of that mighty History of Rome in the Middle Ages, but conscience and justice demand that his chapter upon this subject be dealt with as it deserves.
The striking talents of Gregorovius are occasionally marred by the egotism and pedantry sometimes characteristic of the scholars of his nation.

He is too positive; he seldom opines; he asserts with finality the things that only God can know; occasionally his knowledge, transcending the possible, quits the realm of the historian for that of the romancer, as for instance--to cite one amid a thousand--when he actually tells us what passes in Cesare Borgia's mind at the coronation of the King of Naples.

In the matter of authorities, he follows a dangerous and insidious eclecticism, preferring those who support the point of view which he has chosen, without a proper regard for their intrinsic values.
He tells us definitely that, if Alexander had not positive knowledge, he had at least moral conviction that it was Cesare who had killed the Duke of Gandia.

In that, again, you see the God-like knowledge which he usurps; you see him clairvoyant rather than historical.

Starting out with the positive assertion that Cesare Borgia was the murderer, he sets himself to prove it by piling up a mass of worthless evidence, whose worthlessness it is unthinkable he should not have realized.
"According to the general opinion of the day, which in all probability was correct, Cesare was the murderer of his brother." Thus Gregorovius in his Lucrezia Borgia.