This is the week of the furrowed brow. Tony Blair's forehead has been working late into the night, crinkling, wrinkling and scrunching up as he battles with how he can marry his party and his conscience with an argument for the invasion of Iraq. Whether or not we agree with his pro-American stance, we almost all believe he is genuinely wrestling with a personal predicament. His furrowed forehead tells us so.
Contrast the hardworking forehead of our PM with that of foreign secretary Jack Straw. The latter displays a distinct absence of corrugation, lending Straw a certain lack of seriousness and contemplation. Doesn't he realise the significance of the situation he is leading us into? Without evidence of furrows, we simply don't believe he's even aware of any moral quandaries.
The forehead is the map of the mind, and a furrowed brow is a reliable outer sign of inner thought. Try really concentrating without furrowing your brows - it's almost impossible. The forehead's activator is the corrugator muscle, which lowers the brows and pulls them together, causing a frown. Charles Darwin, in The Expression of Emotion in Man and Animals, accurately called the corrugator the "muscle of difficulty": frowning occurs when we are faced with many different challenges, mental and physical.
In our assessment of someone's character, not only the movement but the size of the forehead matters. The forehead is formed by the frontal bone of the skull, accommodating the frontal lobes of the brain. An imposing forehead not only shows depth of thought but also implies great intelligence. The prophet Mohammed's forehead was said to be large and prominent. One of the most venerated foreheads belonged to the poet WH Auden; it was impressively channelled, like a beautiful old tree. In the tradition of well-bred intellectuals, modern philosopher Alain de Botton also has a very high forehead. It's as if he's superhuman: brainy aliens are always imagined with grossly extended foreheads. Conversely, shortened foreheads are associated with a primitive species of humanity, such as Neanderthal man. Portraying someone with a low forehead was a way to display their ignorance and criminal tendencies; cartoons of the Irish in 19th-century magazines drew them with short brows, making them seem stupid and dishonest.
But prominent foreheads aren't always considered desirable. As a girl growing up, my mother often used to reprimand me: "Don't frown, darling. It'll ruin you." Men may be deemed attractive by having expression above their eyes (actor Jack Nicholson's eyebrows are celebrated for their hyperactivity), but women should be smooth browed, suggesting calmness. That is, presumably, Botox's huge appeal. This new cosmetic drug, injected into the forehead, paralyses the muscles so you simply cannot form a frown anymore. Hollywood agents are complaining that actors now have a limited range of expression due to an overindulgence in these jabs.
It is tempting to see Botox as part of a long tradition of anointing the brow with magical potions. Women in Ancient Egypt tattooed henna designs on their temples. Christian baptism usually involved pouring the baptismal water over the forehead, a sacred spot. Roman Catholics receive the mark of the cross on their foreheads on Ash Wednesday. In Hindu tradition, the centre of the forehead is the location of the third eye, and considered a place of spiritual insight. Muslims touch their foreheads to the floor when bowing towards Mecca.
Straw neither touches his brow nor has been Botoxed, but he might as well have been for all his forehead reveals. Other politicians are outshining him; even former foreign secretary Robin Cook, with his protuberant brow, is coming to the fore as a person of principle. And Blair's personal and political battles in the Middle East are clearly written not in, but above his eyes.
The corrugator says it all. If you want to know a politician's moral character, don't read their lips. Look at their foreheads.