Herbert Spencer,
The Principles of Biology — Chapter II.6
(1898)
“ What is an individual? is a question which many readers will think it easy to answer. Yet it is a question that has led to much controversy among Zoologists and Botanists, and no quite satisfactory reply to it seems possible. As applied to a man, or to any one of the higher animals, which are all sharply-defined and independent, the word individual has a clear meaning: though even here, when we turn from average cases to exceptional cases—as a calf with two heads and two pairs of fore-limbs—we find ourselves in doubt whether to predicate one individuality or two. ”
