1477. There is one essential difference, however, between the landscape-gardener and the painter, which ought never to be lost sight of by the former, and this is, that the materials with which he works are always changing, while those of the artist are fixed. Thus, for example, the landscape-painter can introduce trees of any particular height or colour that he thinks necessary to produce a particular effect in his landscape; but the trees introduced by the landscape-gardener will vary in height and form every year, and in colour every season. It is, therefore, necessary for the landscape-gardener to consider all these changes before he begins to plant; and it is obvious that even with all the consideration that he can give them, they must occasion a degree of uncertainty in his art, from which the landscape-painter is free.
