Mantegazza, P. (1891). Expression of hatred, of cruelty, and of passion. In P. Mantegazza, The contemporary science series. Physiognomy and expression (pp. 159-179). New York, NY, US: Scribner & Welford.
http://dx.doi.org/10.1037/14106-013
Hatred is to love in the domain of the passions what pain is to pleasure in the domain of sensations ; and the expression of hatred must be the opposite of that of love, just as the feelings which they have to manifest are in absolute contradiction. This study, proceeding by comparison and antithesis, would be very easy if we had formed for ourselves a conception of hatred drawn only from observation. But in thinking of hatred we are distracted from a healthy judgment by the influence of ethical and religious ideas, which have accustomed us to look on hatred as a sin. On the contrary, every animal, every man born under the sun must and can hate, provided that he has formed a right conception of hatred, of shrinking from, of reaction against that which threatens and offends us. For the present I may be permitted to sketch the expression of one of the most powerful human energies, whence more than a half of the history of humanity is derived. (PsycINFO Database Record (c) 2016 APA, all rights reserved)