The desire to see for the sake of seeing is with most people the only desire to be gratified; hence the delight in detail. - Alfred Horsley Hinton

...strictly speaking, tone is the relative lightness and darkness due to the effect of light governed by atmosphere, and has nothing to do with the relative lightness and darkness or relative value with which various colours appear when compared with each other.

We know the mountain peaks are lofty, and we think of them so, and we mentally enlarge them, but not the cottage at their foot, or the trees half way up.

…the strongest part of a picture is the sensation and the feeling which it creates, this being done through the agency of certain familiar objects more or less accurately depicted and represented with more or less completeness.
The MOTIVE, then, in all pictorial work is to convey some thought or idea or sensation by means of a chosen subject.