Yet the distinction is modern. In classic times there was no such distinction. The “sciences”—reasonably, as we may now see, and not fancifully as was afterwards supposed—were “the arts of the mind.” In the Middle Ages the same liberal studies—grammar, logic, geometry, music, and the rest—could be spoken of either as “sciences” or as “arts,” and for Roger Bacon, who in the thirteenth century was so genuine a man of science, every branch of study or learning was a “scientia.” I am inclined to think that it was the Mathematical Renaissance of the seventeenth century which introduced the undue emphasis on the distinction between “science” and “art.” “All the sciences are so bound together,” wrote Descartes, the banner-bearer of that Renaissance, in his “Règles pour la Direction de l’Esprit,” “that it is much easier to learn them all at once than to learn one alone by detaching it from the others.” He added that we could not say the same of the arts. Yet we might perhaps say of arts and sciences that we can only understand them all together, and we may certainly say, as Descartes proceeded to say of the sciences alone, that they all emanate from the same focus, however diversely coloured by the media they pass through or the objects they encounter. At that moment, however, it was no doubt practically useful, however theoretically unsound, to overemphasise the distinction between “science,” with its new instrumental precision, and “art.”[26] At the same time the tradition of the old usage was not completely put aside, and a Master of “Arts” remained a master of such sciences as the directors of education succeeded in recognising until the middle of the nineteenth century. By that time the development of the sciences, and especially of the physical sciences, as “the discovery of truth,” led to a renewed emphasis on them which resulted in the practical restriction of the term “art” to what are ordinarily called the fine arts. More formally, science became the study of what were supposed to be demonstrable and systematically classifiable truths regarding the facts of the world; art was separated off as the play of human impulses in making things. Sir Sidney Colvin, in the “Encyclopædia Britannica,” after discussing the matter (which Mill had already discussed at length in his “Logic” and decided that the difference is that Science is in the Indicative Mood and Art in the Imperative Mood), concluded that science is “ordered knowledge of natural phenomena and of the relations between them,” or that “Science consists in knowing, Art consists in doing.” Men of science, like Sir E. Ray Lankester, accepted this conclusion. That was as far as it was possible to go in the nineteenth century.