'Platonic love', to Plato, does not mean friends breath a sigh of relief because they share no erotic entanglements. Friends, you fool yourselves, he believes. Rather, it means sublimating the erotic energy between two people to pursue not each other, but together, life itself.

This much is clear from, say, a read of the Phaedrus, and it is handy that Jay Kennedy's analysis of the musical patterns embedded in Plato's Symposium confirm that Plato was not against human love, as the view associated with the scholar Gregory Vlastos has it, but wished to channel it. (I see that Kennedy is still 'cracking the Plato code' and discovering 'hidden doctrines', which is good marketing, won lots of headlines last year, I hear secured a big book deal and Holywood interest because it is fun, in a Dan Brown way - and like Brown, wildly overplays the hand.)

'Plato divided each of his writings into 12 parts,' Kennedy explains, 'inserting a symbol marking a musical note at each twelfth. At harmonious notes he placed positive ideas such as love and goodness, while at dissonant notes he placed negative ideas such as rejection, quarrelling and evil.' In the Symposium, comments about trading sex for favour or advantage are placed at dissonant notes; expressions of erotic love's abiding desire for another's soul are placed at harmonious notes.

Platonic love is, in fact, a notion of relatively recent invention. Kennedy continues: 'At the beginning of the modern era, women cleverly used Plato’s reputation as a genius to get men to pay attention to their minds. Platonic love was an argument for not settling down and allowing women to participate in arts and culture in the royal court. When sex often meant an early death, Plato was a licence for having more fun.'

Which also goes to show that historic attitudes towards sex are more subtle and inventive than we moderns, so proud of our free attitudes towards love, can allow them to be. This came out in Will Self's review of Catherine Kakim's Honey Money: The Power of Erotic Capital. He notes that for Hakim 'Christian monogamy' is just a strategy to ensure that all men, who are more ugly on average, get a woman, who are more beautiful.

Except that, if anything, the Biblical imperative is not for monogamy but for not marrying at all. As Peter Brown shows in his brilliant The Body and Society, when Jesus discouraged marriage by example (sorry Dan) and Paul by teaching, they encouraged a practice that was liberating for women, for whom marriage - like medieval sex - often meant early death.

It was also socially disruptive, because women, on average, had to have quite a few children by quite a young age, just to preserve population levels.

(Image: Mosaïque de la muse Euterpe de la salle Rameau)