9) "Libido is an expression taken from the theory of the emotions. We call by that name the energy, regarded as a quantitative magnitude (though not at present actually measurable), of those instincts which have to do with all that may be comprised under the word 'love'. The nucleus of what we mean by love naturally consists (and this is what is commonly called love, and what the poets sing of) in sexual love with sexual union as its aim. But we do not separate from this - what in any case has a share in the name 'love' - on the one hand, self-love, and on the other, love for parents and children, friendship and love for humanity in general, and also devotion to concrete objects and to abstract ideas. Our justification lies in the fact that psycho-analytic research has taught us that all these tendencies are an expression of the same instinctual impulses; in relations between the sexes these impulses force their way towards sexual union, but in other circumstances they are diverted from this aim or are prevented from reaching it, though always preserving enough of their original nature to keep their identity recognizable (as in such features as the longing for proximity, and self-sacrifice).
We are of opinion, then, that language has carried out an entirely justifiable piece of unification in creating the word 'love' with its numerous uses, and that we cannot do better than take it as the basis of our scientific discussions and expositions as well. By coming to this decision, psycho-analysis has let loose a storm of indignation, as though it had been guilty of an act of outrageous innovation. Yet it has done nothing original in taking love in this 'wider' sense. In its origin, function, and relation to sexual love, the 'Eros' of the philosopher Plato coincides exactly with the love-force, the libido of psycho-analysis, as has been shown in detail by Nachansohn (1915) and Pfister (1921); and when the apostle Paul, in his famous epistle to the Corinthians, praises love above all else, he certainly understands it in the same 'wider' sense. But this only shows that men do not always take their great thinkers seriously, even when they profess most to admire them.
Psycho-analysis, then, gives these love instincts the name of sexual instincts, a potiori and by reason of their origin. The majority of 'educated' people have regarded this nomenclature as an insult, and have taken their revenge by retorting upon psycho-analysis with the reproach of 'pan-sexualism'. Anyone who considers sex as something mortifying and humiliating to human nature is at liberty to make use of the more genteel expressions 'Eros' and 'erotic'. I might have done so myself from the first and thus have spared myself much opposition. But I did not want to, for I like to avoid concession to faintheartedness. One can never tell where the road may lead one; one gives way first in words, and then little by little in substance too. I cannot see any merit in being ashamed of sex; the Greek word 'Eros', which is to soften the affront, is in the end nothing more than a translation to our German word Liebe [love]; and finally, he who knows how to wait need make no concessions."