It is a recognized principle that every medium of art expression should be treated with due regard to its nature and properties.  The sculptor varies his technique according as he works in wood, granite, or marble; the painter handles his water-color in quite another manner than that he would employ on an oil-painting of the same subject; and the architect, with the subtle sense of the craftsman, carries this principle to such a fine issue as to impart an individual expression even to particular woods.  He knows that what may be an admirable design when executed in brass may be a very bad one in wrought-iron and is sure to be an absurdity in wood.  An artistic motive for a silver flagon, too, is likely to prove ugly for pottery or cut-glass, and so on.  There is a genius, born of its particular properties, in every medium, which demands individual expression.  Observe, therefore, that Art is not satisfied with mere unrelated beauty of form or color.  It requires that the result confess some sensible relation to the means by which it has been obtained; and in proportion as it does this, it may claim to possess that individual and distinctive charm which we call “Style.”  It may be said, therefore, that the technical limitations of particular mediums impose what might properly be called natural conventions; and while misguided ambition may set these conventions aside to hammer out effects from an unwilling medium, the triumph is only mechanical; Art does not lie that way.

[Side note:  The Province of the Pen]

Ought the pen, then, to be persuaded into the province of the brush?  Since the natures of the two means differ, it does not stultify the water-color that it cannot run the deep gamut of oil.  Even if the church-organ be the grandest and most comprehensive of musical instruments we may still be permitted to cherish our piano.  Each has its own sphere, its own reason for being.  So of the pen,—­the piccolo flute of the artistic orchestra.  Let it pipe its high treble as merrily as it may, but do not coerce it into mimicking the bassoon.

[Illustration:  FIG. 1 JOSEPH PENNELL]

Pen drawing is most apt to lose its individuality when it begins to assume the characteristics of wash-drawing, such as an elaborate massing of grays, small light areas, and a general indirectness of method.  A painter once told me that he was almost afraid to handle the pen,—­“It is so fearfully direct,” he said.  He understood the instrument, certainly, for if there is one characteristic more than another which should distinguish pen methods it is Directness.  The nature of the pen seems to mark as its peculiar function that of picking out the really vital features of a subject.  Pen drawing has been aptly termed the “shorthand of Art;” the genius of the pen-point is essentially epitome.