We love looking at people – the old notion that physiognomy is a key to psychology has never really left us. So great is Ottavio Leoni’s scrutiny of his contemporaries’ faces that you leave this little exhibition feeling that you’ve got to know, on intimate terms, some of the most powerful and remarkable people of the seventeenth century.

A pope, a scientist, an artist, a roué and a rake: the gathering has all the elements for a farce. Ottavio Leoni, whose engraved portraits could be found in every household in Rome, captured likeness and character with sensitivity but without obsequiousness. He engraves as if he were modelling in soft chalk, meticulously rendering the surface of the person’s face. Nothing escapes his eye, for to whitewash a face is to whitewash the character behind it. Galileo’s drooping eye, Guercino’s greasy hair and crossed eyes, Urban VIII’s soft face all give us clues as to who these people were.

Don Antonio Barberini, the man who promoted Rome’s theatrical life and who indulged in lovers male and female, is here depicted as a passionate, though disconcertingly sensitive-looking man. His slightly podgy face, a nose to make Freudians think, and a wonderful mop of hair all speak of his rakish life. How different from his brother! A brow corrugated by years of stern thought and a sharp witted aquiline countenance, quite out of place in the soft, pillowy faces of Urban VIII and his Nipote.

And then the man himself, Ottavio Leoni, whose self-portrait is pre-eminently flattering. Placed within the hallmark of his engraved plates – a polygonal frame with the stamp “eques Octavius Leonus Roman pictor fecit”, like the mark of a fine chocolatier – his face and hair are beautifully rendered, though no epidermal accidents or physical peculiarities are to be seen. If you haven’t met a pope, artist or Galileo, here’s your chance: they are waiting at the Fitzwilliam.