(4.) Another aspect of things vividly realised by Lucretius is that of their individuality. It was in the atomic philosophy, that the thought of 'the individual' first rose into prominence. The meaning of the word 'atom' is simply 'individual.' The sense of each separate existence is not merged in the conception of law, of change, or of the immensity of the universe. The atoms are not only infinite in number, they are also varied in kind and powerful in solid singleness,--'solida pollentia simplicitate.' From their variety and individuality the variety and individuality in Nature emerge. No two classes and no two single objects are exactly alike. Between any two of the birds that gladden the sea-shore, the river banks, or the woods, there is some difference in outward appearance-- Invenies tamen inter se differre figuris.[440] Each individual of a flock is different from every other, and by this difference only can the mother recognise her offspring. This sense of individuality intensifies the pathos of many passages in the poem. By regarding each being as having an existence of its own, the poet enters with sympathy into the feelings of all sentient existence,--of dumb animals as well as of human creatures. The freshness and distinctness of all his pictures from Nature are the result of an eye trained by his philosophy to see each thing not only as part of the universal life, but as existing in and for itself. (5.) The thought, also, of the infinite subtlety of combination in the elements and forces of the world acts powerfully on his imagination. The individuality of things depends on the fact that no two are composed of exactly the same elements, combined in the same way. The infinity of the elements, the immensity of the spaces in which they meet, and the infinite possibilities in their modes of combination result in the endless variety of beauty and wonder which the world presents to the eye. The epithet 'daedala,' by which this subtlety is expressed is applied not only to Nature, but to the earth as the sphere in which the elements are most largely mixed, and the creative forces most powerfully active. The varied loveliness of the world,--the 'varii lepores,' by which the eye is gratified and relieved,--are the result of the variety in the elements and the infinite subtlety in their modes of combination. Their invisibility and inscrutable action enhance the imaginative sense of the power and beauty resulting from these causes.