The next contrast I shall mention is that of light and dark, not in shadow and shade, but of a variety in colouring observable in nature, and well worth cultivating in the art of gardening, although difficult to represent in painting. Of this I shall enumerate several kinds. Firstly. The difference of a leaf with the light shining full upon it, which renders it an opaque object, and the same leaf seen transparent, by the light shining through it*.
*[Having, one day, when at Holwood, pointed this out to Mr. William Pitt, as a source of the delight we experience in a sunny day, from an open trellis of vines overhead, or the foliage in the roof of a conservatory, he was so forcibly struck with the remark, that he made several experiments with leaves of different shapes and tints, some of which, from the opaquer ramification of their fibres, or other circumstances of texture, &c. became new objects of delight to a mind like his, capable of resorting to the beauties of nature, as a relief from the severer duties of his arduous situation.]