books entitled 'Science in
Arcady,' 'Vignettes from Nature,' 'The Evolutionist at Large,' and
'Colin Clout's Calendar.' In his preface to 'Vignettes from Nature,' he
says that the "essays are written from an easy-going, half-scientific
half-aesthetic standpoint." In this spirit he rambles in the woods, in
the meadows, at the seaside, or upon the heather-carpeted moor, finding
in such expeditions material and suggestions for his lightly moving
essays, which expound the problems of Nature according to the theories
of his acknowledged masters. A fallow deer grazing in a forest, a
wayside berry, a guelder rose, a sportive butterfly, a bed of nettles, a
falling leaf, a mountain tarn, the hole of a hedgehog, a darting
humming-bird, a ripening plum, a clover-blossom, a spray of sweet-briar,
a handful of wild thyme, or a blaze of scarlet geranium before a cottage
door, furnish him with a text for the discussion of "those biological
and cosmical doctrines which have revolutionized the thought of the
nineteenth century," as he says in substance.

Somewhat more scientific are 'Psychological Aesthetics,' 'The Color
Sense,' 'The Color of Flowers,' and 'Flowers and their Pedigrees'; and
still deeper is 'Force and Energy' (1888), a theory of dynamics in which
he expresses original views. In 'Psychological Aesthetics' (1877), he
first seeks to explain "such simple pleasures in bright color, sweet
sound, or rude pictorial imitation as delight the child and the savage,
proceeding from these elementary principles to the more and more complex
gratifications of natural scenery, painting, and poetry." In 'The Color
Sense' he defines all that we do not owe to the color sense, for example
the rainbow, the sunset, the sky, the green or purple sea, the rocks,
the foliage of trees and shrubs, hues of autumn, effects of iridescent
light, or tints of minerals and precious stones; and all that we do owe,
namely, "the beautiful flowers of the meadow and the garden-roses,
lilies, cowslips, and daisies; the exquisite pink of the apple, the
peach, the mango, and the cherry, with all the diverse artistic wealth
of oranges, strawberries, plums, melons, brambleberries, and
pomegranates; the yellow, blue, and melting green of tropical
butterflies; the magnificent plumage of the toucan, the macaw, the
cardinal-bird, the lory, and the honey-sucker; the red breast of our
homely robin; the silver or ruddy fur of the ermine, the wolverene, the
fox, the squirrel,