In a state of nature instinct is enough. Why bother
? The quick sight, the zest of rapid motion through an aerial substance, the rising ecstasy of seasonal parenthood, the search for food and drink fill a bird's life. It needs no more ; but the grey-matter is there all the time as the anatomists tell us, and in considerable weight, bulk and complexity. (especially in the rook as especially in the spaniel) and its uses may be evoked when circumstances persuade. The subject is foolishly confused by dragging in insects. The gulf between mammal or bird and insect (which has no physical brain to speak of, but instead nerve-nuclei here there or anywhere) is vastly greater than between man and monkey or dog. The conclusion from the structure as from the ways of dogs and birds, is that they possess reason but cannot reason, at any rate beyond the boundary of the senses ; for that final development, language is a " condition precedent."