This curtailing of class hours was characteristic of the Society's system. In 1567 the General Father Francis Borgia wrote, through his secretary Polanco, correcting, in this respect, a school-regulation which had been followed in the lower classes of the German Province. The secretary writes: "It is found by experience, in the schools of the Company, that to teach three consecutive hours in the forenoon, and three more in the afternoon, is injurious to the health of our Masters, and does no good to the health of the scholars; for which reason it is now ordained that in our schools the morning classes shall not last longer than two and a half hours, and the same in the afternoon."[224] Nothing intensifies more the results of studies than concentration, nor dissipates them more than division of attention, while a given pursuit is in progress. This principle applies to the number of courses taken up at one time, the conduct of private studies in any single course, and the degree to which the appointed teachers and the standard authors have full justice done them. On this head, the critics of 1586 give recommendations, derived from the Constitution, for the direction of all the students in general, and for the members of the Order in particular. The recommendations are embodied briefly in the _Ratio Studiorum_.[225] With Aristotle in Philosophy, or with St. Thomas in Theology, one commentary is to be designated, and that a specially chosen author, suited to the individual's capacity. In the second year of Theology, one of the Fathers of the Church can be added, "to be read at odds and ends of time, or after the fatigue of a long stretch of study. Another can be substituted, if after a while they ask for another. But care should be taken that they do not spend too much time on this reading, as if they were getting up a sermon."[226] All this, no doubt, tends to make the student "a man of one book," who, as the adage says, is much to be feared. However, when he goes through every course, and is everywhere a man of concentrated attention, while, for the purpose of public disputation and the attempted refutation of his own and the Professor's conclusions, the side avenues of various authors and systems are studiously and necessarily kept open, it is probable that, after being "a man of one book," in many courses successively, he will also be well-rounded by the time his formation is complete. With students in general, this can be accomplished by the age of twenty-five; with the Jesuits themselves, about the age of thirty-three.