In April 1528, when Philip was eleven months old, he received the oath of allegiance as heir to the crown from the Cortes of Castile, and from that time until the return of his father to Spain in 1533 the royal infant remained under the care of his mother and one of her Portuguese ladies, Doña Leonor de Mascarenhas, to whom Philip in after-life was devotedly attached. He was even then a preternaturally grave and silent child, with a fair pink-and-white skin, fine yellow hair, and full blue lymphatic eyes, rather too close together. It is no uncommon thing for princes to be represented as prodigies, but Philip seems, in truth, to have been really an extraordinary infant, and exhibited great aptitude for certain studies, especially mathematics. Charles on his arrival in Spain decided to give to his heir a separate household and masters who should prepare him for the duties of his future position. A list was made of the principal priestly professors of the Spanish universities, which was gradually reduced by elimination to three names. These were submitted to the empress for her choice, and she selected Dr. Juan Martinez Pedernales (which name = flints, he ingeniously Latinised into Siliceo), a professor of Salamanca, who was appointed tutor to the prince, with a salary of 100,000 maravedis a year. The emperor probably knew little of the character of his son’s tutor. He had intended in the previous year to appoint to the post a really eminent scholar, the famous Viglius, but did not do so. Whatever may have been Siliceo’s virtues, and according to priestly historians they were many, the emperor had subsequently a very poor opinion of the way in which he had performed his duty. In a private letter from Charles to his son ten years afterwards, to which other reference will be made, the emperor says that “Siliceo has certainly not been the most fitting teacher for you. He has been too desirous of pleasing you. I hope to God that it was not for his own ends”; and again, “He is your chief chaplain, and you confess to him. It would be bad if he was as anxious to please you in matters of your conscience as he has been in your studies.” But Philip evidently liked his tutor, for later he made him Archbishop of Toledo and Primate of Spain. The prince must have been an apt pupil in the studies which most attracted him. He was never a linguist of any proficiency, but could read and write Latin well at quite an early age, and certainly understood French and Italian. But he was a Spaniard of Spaniards, and nothing shows the strict limitations of his capacity more than the clumsiness with which he expressed himself even in his own language, although he frequently criticised and altered the words and expressions employed by his secretaries.