In London's National Gallery, there is a painting called ‘Philosopher’. It shows a swarthy, dark haired youngish man in a cloak, romantically framed by an empty sky. He is standing by a column on which are inscribed the words ‘Aut tace, aut loquere meliora silentio’ – ‘Be silent, unless to speak would be better than silence.’

One might wonder why this message might have seemed appropriate to the subject. Have philosophers been noted for a reticence to speak because of some fear that what they have to say may not be better than silence? Have those who have listened to philosophers invariably concluded that what they heard was actually better than silence might have been?

There was a philosopher who ordered silence on certain matters, and others who preached that much of what people normally said was meaningless. But these views did little to inhibit those who professed them from holding forth at great length on other topics, or even it has to be said, on the topics which were officially banned or characterised as meaningless.

Philosophers might like to think of themselves as sage and reticent, except where there is something important to be said; though looking at the numbers of words which flow from their word-processors, and which they are only too ready to publish, one doubts that many of them ever thought that the ‘tace’ part of the epigraph ever applied to them personally.

However, there is another thought. ‘Philosopher’, which dates from 1645, is said to be a self-portrait of its painter, Salvator Rosa, a man famous his flamboyance and braggadocio, and hardly noted for periods of reflective silence. Is his painting intended as a joke at his own expense and, coincidentally, at that of philosophy too?