the man who paints has learned the art of painting? Is there any seed or root that the earth cannot receive and bring to germination by its warmth, if the gardener understand when, where, and how it should be sown? Moreover, there is in the world no rock or tower of such a height that it cannot be scaled by any man (provided he lack not feet) if ladders are placed in the proper position or steps are cut in the rock, made in the right place, and furnished with railings against the danger of falling over. It is true that very few scale the heights of wisdom, though many start gaily on the journey, and that those who get any distance do so at the cost of toil, loss of breath, weariness, and giddiness; this, however, does not prove that there is anything inaccessible to the human intellect, but only that the steps are not well disposed, or are insufficient, dangerous, and in bad repair in other words, that the method is complicated. It is an undoubted fact that any man can attain any height that he may desire by means of steps that are properly disposed, sufficient in number, solid, and safe.
16. It will be urged, Some men have such weak intellects that it is not possible for them to acquire knowledge. I answer, It is scarcely possible to find a mirror so dulled that it will not reflect images of some kind, or for a tablet to have such a rough surface that nothing can be inscribed on it. Again, if the mirror be soiled by dirt or by spots, it must first be cleaned; if the tablet be rough, it must be polished; both will then perform their functions. In the same way, if teachers take sufficient trouble, men will become polished, and finally all men will understand all things (I stand firmly by my watchword because my fundamental principles prove correct). There is naturally a difference in intellects, and while those who are slow may only be able to attain to one stage of knowledge, the more gifted advance higher and higher, from one object to another, and collect new observations which are of great utility. Finally, though there may be some intellects that do not admit of culture, just as knotty
