If we conceive that anyone takes delight in something, which only one person can possess, we shall endeavour to bring it about, that the man in question shall not gain possession thereof.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

““ Everything, ” we are told, “ in so far as it is in itself, endeavours to persevere in its own being. ” The psychology of Book III is entirely egoistic. “ He who conceives that the object of his hate is destroyed will feel pleasure. ” If we conceive that anyone takes delight in something, which only one person can possess, we shall endeavour to bring it about, that the man in question shall not gain possession thereof. “ Hatred is increased by being reciprocated, and can on the other hand be destroyed by love. ”
The last two books of the Ethics, entitled respectively “ Of human bondage, or the strength of the emotions ” and “ Of the power of the understanding, or of human freedom, ” are the most interesting.” source