From The Philosopher's Mail: (I think it is Alain de Botton writing but am not sure)
You are introduced to someone at a conference. They look nice and you have a brief chat about the theme of the keynote speaker. But already, partly because of the slope of their neck and a lilt in their accent, you have reached an overwhelming conclusion. Or, you sit down in the carriage – and there, diagonally opposite you – is someone you cannot stop looking at for the rest of a journey across miles of darkening countryside. You know nothing concrete about them. You are going only by what their appearance suggests. You note that they have slipped a finger into a book (The Food of the Middle East), that their nails are bitten raw, that they have a thin leather strap around their left wrist and that they are squinting a touch short-sightedly at the map above the door. And that is enough to convince you. Another day, coming out of the supermarket, amidst a throng of people, you catch sight of a face for no longer than eight seconds and yet here too, you feel the same overwhelming certainty – and, subsequently, a bittersweet sadness at their disappearance in the anonymous crowd.
Crushes: they happen to some people often and to almost everyone sometimes. Airports, trains, streets, conferences – the dynamics of modern life are forever throwing us into fleeting contact with strangers, from amongst whom we pick out a few examples who seem to us not merely interesting, but more powerfully, the solution to our lives. This phenomenon – the crush – goes to the heart of the modern understanding of love. It could seem like a small incident, essentially comic and occasionally farcical. It may look like a minor planet in the constellation of love, but it is in fact the underlying secret central sun around which our notions of the romantic revolve.
A crush represents in pure and perfect form the dynamics of romantic philosophy: the explosive interaction of limited knowledge, outward obstacles to further discovery – and boundless hope.
The crush reveals how willing we are to allow details to suggest a whole. We allow the arch of someone’s eyebrow to suggest a personality. We take the way a person puts more weight on their right leg as they stand listening to a colleague as an indication of a witty independence of mind. Or their way of lowering their head seems proof of a complex shyness and sensitivity. From a few cues only, you anticipate years of happiness, buoyed by profound mutual sympathy.