Lionello transmitted to Poggio the hundred ducats, at which he appreciated his copy of the epistles of Jerome. He intimated to him, however, that some of the learned men of Ferrara thought the price an extravagant one; and he desired that it might be understood, that in acceding to the terms proposed by his correspondent, he intended to make him a present of the excess above the real value of the book. In reply to these observations, Poggio maintained the correctness of his estimation, in opposition to the judgment of the Ferrarese connoisseurs, which he treated with great contempt; and humorously observed, that he thankfully accepted the gift mentioned by Lionello, not on account of its intrinsic value, but as an earnest of future munificence; “for,” said he, “it is the custom of worthy princes, such as you are, to persevere in what they have well begun.”[343] If the ducat be estimated at ten shillings English money, the epistles of Jerome were purchased by Lionello at the expense of fifty pounds sterling.[344] From the history of Filelfo it appeals, that at this time the salary of a public professor of literature rarely exceeded four hundred ducats; so that the price of a couple of volumes absorbed one-fourth of the sum which was deemed an adequate annual recompence for the services of a man of consummate learning. The exhibition of these facts will demonstrate the difficulties which obstructed the paths of learning in the fourteenth and fifteenth centuries. It will also tend to make the modern scholar sensible of the tribute of gratitude which he owes to the inventor of the typographic art.