The Elements of Perspective / arranged for the use of schools and intended to be read in connection with the first three books of Euclid

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THE COMPLETE WORKS OF JOHN RUSKIN
ELEMENTS OF DRAWING AND PERSPECTIVE THE TWO PATHS UNTO THIS LAST MUNERA PULVERIS SESAME AND LILIES ETHICS OF THE DUST
NATIONAL LIBRARY ASSOCIATION NEW YORK CHICAGO
ARRANGED FOR THE USE OF SCHOOLS
AND INTENDED TO BE READ IN CONNECTION WITH THE FIRST THREE BOOKS OF EUCLID.
For some time back I have felt the want, among Students of Drawing, of a written code of accurate Perspective Law; the modes of construction in common use being various, and, for some problems, insufficient. It would have been desirable to draw up such a code in popular language, so as to do away with the most repulsive difficulties of the subject; but finding this popularization would be impossible, without elaborate figures and long explanations, such as I had no leisure to prepare, I have arranged the necessary rules in a short mathematical form, which any schoolboy may read through in a few days, after he has mastered the first three and the sixth books of Euclid.
INTRODUCTION.
When you begin to read this book, sit down very near the window, and shut the window. I hope the view out of it is pretty; but, whatever the view may be, we shall find enough in it for an illustration of the first principles of perspective (or, literally, of “looking through”).
Every pane of your window may be considered, if you choose, as a glass picture; and what you see through it, as painted on its surface.
And if, holding your head still, you extend your hand to the glass, you may, with a brush full of any thick color, trace, roughly, the lines of the landscape on the glass.
But, to do this, you must hold your head very still. Not only you must not move it sideways, nor up and down, but it must not even move backwards or forwards; for, if you move your head forwards, you will see more of the landscape through the pane; and, if you move it backwards, you will see less : or considering the pane of glass as a picture, when you hold your head near it, the objects are painted small, and a great many of them go into a little space; but, when you hold your head some distance back, the objects are painted larger upon the pane, and fewer of them go into the field of it.