“At a certain point in every person’s amours,” E.B. White and James Thurber wrote in their terrific 1929 satirical take on how to tell love from lust, “the question arises: ‘Am I in love, or am I merely inflamed by passion?’” And yet the strangest, most paradoxical thing is that there is nothing “mere” about being inflamed by passion — infatuation, as much as it may drive us mad, is a singularly potent and utterly addictive drug with the capacity to narrow our focus so spectacularly as to reduce the entirety of the world to the object of our desire.

Our tendency to mistake such infatuation for love is one of the gravest mistakes the human heart can make, and one of the most common — as philosopher Erich Fromm observed in his indispensable 1956 treatise on the art of loving, misguided lovers all too frequently “take the intensity of the infatuation, this being ‘crazy’ about each other, for proof of the intensity of their love, while it may only prove the degree of their preceding loneliness.”

Two centuries after Stendhal wrote brilliantly about the psychology of infatuation, the English writer, actor, and Downton Abbey creator Julian Fellowes captures the paradox of this delicious delusion in an exquisite passage from his novel Snobs (public library). He writes:

Lust, that state commonly known as “being in love,” is a kind of madness. It is a distortion of reality so remarkable that it should, by rights, enable most of us to understand the other forms of lunacy with the sympathy of fellow-sufferers. And yet, as we all know, it is a madness that, however ferocious, seldom, if ever, lasts. Nor, contrary to the popular teaching on the subject, does lust usually give a way to “a deeper and more meaningful love.” There are exceptions of course. Some spouses “love” forever. But, as a rule, if the couple is truly well matched, it gives way to a warm and interdependent friendship enhanced by physical attraction. Should they be ill-sorted it simply fades into boredom or, if they have the misfortune of being married in the interim, dull hatred. But, paradoxically, mad and suffering as one is, and the heat of the flame, few of us are glad as we feel that passion slip away. How many of us, re-meeting objects of desire who once burned a scar through seasons and even years, whose voices on the telephone could start up flights of butterflies, whose slightest expression could set off a petal of tremulous sexual bells in our vitals, search our inner selves in vain for the least attraction to the face before us? How many of us, having cried bitter, rancid tears over a failed love, are actually disappointed when we discover, seeing the adored one again, that all trace of their power over us is gone? How often one has resisted the freedom-giving knowledge that they have actually begun to irritate us as that seems like the worst kind of disloyalty to our own dreams. No, while most people have been at their unhappiest while in love, it is nevertheless the state the human being yearns for above all.

Complement with Robert Graves on love and lust, John O’Donohue on how desire vitalizes us, and Susan Sontag on love, sex, and the world between.