_Third Phase._—Under its intellectual form, sympathy is an agreement in feelings and actions, founded on unity of representation. The law of development is summed up in Spencer’s formula, “The degree and range of sympathy depend on the clearness and extent of representation.”[145] I should, however, add: on condition of being based on an emotional temperament. This last is the source _par excellence_ of sympathy, because it vibrates like an echo; the active temperament lends itself less to such impulses, because it has so much to do in manifesting its own individuality that it can scarcely manifest those of others; finally, the phlegmatic temperament does so least of all, because it presents a minimum of emotional life; like Leibnitz’s monads, it has no windows. Footnote 145: _Principles of Psychology_, vol. iv. p. 565. In passing from the emotional to the intellectual phase, sympathy gains in extent and stability. In fact, emotional sympathy requires some analogy in temperament or nature; it can scarcely be established between the timid and the daring, between the cheerful and the melancholic; it may be extended to all human beings and to the animals nearest us, but not beyond them. On the contrary, it is the special attribute of intelligence to seek resemblances or analogies everywhere, to unify; it embraces the whole of nature. By the law of transfer (which we have already studied) sympathy follows this invading march, and comprehends even inanimate objects, as in the case of the poet, who feels himself in communion with the sea, the woods, the lakes, or the mountains. Besides, intellectual sympathy participates in the relative fixity of representation: we find a simple instance of this in animal societies, such as those of the bees, where unity, or sympathy among the members, is only maintained by the perception or representation of the queen. II. Tender emotion marks an important stage in the evolution of affective life; with it we pass beyond the period of the purely egoistic emotions. The date of its appearance, as I have said, is not fixed with certainty; it may be at two months, according to Darwin, who noted at this age one of his characteristic modes of expression, the smile; more probably about nine months (Darwin) or twelve months (Perez), according to definite observations.