Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
Again, do not we ourselves, when unexpectedly called upon to plead, speak while we are thinking what we are to say next, invention of argument, choice of words, rhythm, gesture, delivery, facial expression and movement all being required simultaneously? If all these things can be done with one effort in spite of their diversity, why should we not divide our hours among different branches of study? We must remember that variety serves to refresh and restore the mind, and that it is really considerably harder to work at one subject without intermission. Consequently we should give the pen a rest by turning to read, and relieve the tedium of reading by changes of subject. However manifold our activities, in a certain sense we come fresh to each new subject.
Who can maintain his attention, if he has to listen for a whole day to one teacher harping on the same subject, be it what it may? Change of studies is