But when more force and brilliancy are wanted, some use of your paint in a crumbling, broken manner is necessary, as it catches more light, thus increasing the force of the impression.  Claude Monet and his followers in their search for brilliancy used this quality throughout many of their paintings, with new and striking results.  But it is at the sacrifice of many beautiful qualities of form, as this roughness of surface does not lend itself readily to any finesse of modelling.  In the case of Claude Monet’s work, however, this does not matter, as form with all its subtleties is not a thing he made any attempt at exploiting.  Nature is sufficiently vast for beautiful work to be done in separate departments of vision, although one cannot place such work on the same plane with successful pictures of wider scope.  And the particular visual beauty of sparkling light and atmosphere, of which he was one of the first to make a separate study, could hardly exist in a work that aimed also at the significance of beautiful form, the appeal of form, as was explained in an earlier chapter, not being entirely due to a visual but to a mental perception, into which the sense of touch enters by association.  The scintillation and glitter of light destroys this touch idea, which is better preserved in quieter lightings.

There is another point in connection with the use of thick paint, that I don’t think is sufficiently well known, and that is, its greater readiness to be discoloured by the oil in its composition coming to the surface.  Fifteen years ago I did what it would be advisable for every student to do as soon as possible, namely, make a chart of the colours he is likely to use.  Get a good white canvas, and set upon it in columns the different colours, very much as you would do on your palette, writing the names in ink beside them.  Then take a palette-knife, an ivory one by preference, and drag it from the individual masses of paint so as to get a gradation of different thicknesses, from the thinnest possible layer where your knife ends to the thick mass where it was squeezed out of the tube.  It is also advisable to have previously ruled some pencil lines with a hard point down the canvas in such a manner that the strips of paint will cross the lines.  This chart will be of the greatest value to you in noting the effect of time on paint.  To make it more complete, the colours of several makers should be put down, and at any rate the whites of several different makes should be on it.  As white enters so largely into your painting it is highly necessary to use one that does not change.

The two things that I have noticed are that the thin ends of the strips of white have invariably kept whiter than the thick end, and that all the paints have become a little more transparent with time.  The pencil lines here come in useful, as they can be seen through the thinner portion, and show to what extent this transparency has occurred.  But the point I wish to emphasise is that at the thick end the larger body of oil in the paint, which always comes to the surface as it dries, has darkened and yellowed the surface greatly; while the small amount of oil at the thin end has not darkened it to any extent.