There are also many uses for the mirror in the studio, well known to the artist. One is to look at one's own picture reversed, when faults become more evident; and another, when the model is required to be at a longer distance than the dimensions of the studio will admit, by drawing his reflection in the glass we double the distance he is from us.
The reason the mirror shows the fault of a work to which the eye has become accustomed is that it doubles it. Thus if a line that should be vertical is leaning to one side, in the mirror it will lean to the other; so that if it is out of the perpendicular to the left, its reflection will be out of the perpendicular to the right, making a double divergence from one to the other.
Before we part, I should like to say a word about mental perspective, for we must remember that some see farther than others, and some will endeavour to see even into the infinite. To see Nature in all her vastness and magnificence, the thought must supplement and must surpass the eye. It is this far-seeing that makes the great poet, the great philosopher, and the great artist. Let the student bear this in mind, for if he possesses this quality or even a share of it, it will give immortality to his work.
To explain in detail the full meaning of this suggestion is beyond the province of this book, but it may lead the student to think this question out for himself in his solitary and imaginative moments, and should, I think, give a charm and virtue to his work which he should endeavour to make of value, not only to his own time but to the generations that are to follow. Cultivate, therefore, this mental perspective, without forgetting the solid foundation of the science I have endeavoured to impart to you.
[Transcriber's Note: Index citations in the original book referred to page numbers. References to chapters (Roman numerals) or figures (Arabic numerals) have been added in brackets where possible. Note that the last two entries for "Toledo" are figure numbers rather than pages; these have not been corrected.]
A Albert Dürer, 2, 9. Angles of Reflection, 259 [CLXV]. Angular Perspective, 98 [XLIX] - 123 [LXXII], 133 [LXXX], 170. " " New Method, 133 [LXXX], 134 [LXXXI], 135 [LXXXII], 136 [LXXXIII]. Arches, Arcades, &c., 198 [CXXVI], 200 [CXXVII] - 208 [CXXIII]. Architect's Perspective, 170 [CVIII], 171 [197]. Art Schools Perspective, 112 [LXII] - 118 [LXVI], 217 [CXLI]. Atmosphere, 1, 74 [XXX].