Face of the Devil Hidden in Giotto Fresco

The assumption that this is the devil seems somewhat flawed. It could be the artist slipped in his own face or the face of a friend or sponsor or some prominent figure. Like j says it could have been added later, but there is also the fact that artists of the time didn't necessarily paint the whole of a large fresco like that. They used assistants, often students, to do some of the less important work. Could it be one of them that slipped in the face?

Oh and @Thorfin the phrase "the devil is in the details" is a corruption (probably originating in the 19th century) of an earlier phrase "God is in the details". This is generally taken to mean anything you do, you should do well and carefully. The phrase you quote is often used now to mean that things go wrong where you miss out the little details from your plans. In other words the devil is in the detail that you miss.

also, it was pretty common for artists renovating the frescoes in later years to add their faces hidden somewhere in the images, so it's probably just that...

Soooo... I guess we should consider everyone that has a hooked nose and smiles a devil now?

Was this where Grandma Brunhilda got her saying: "The Devil is in the Details?"

Hard to see from the ground? It's hard to see from the close-up picture, too. I agree with Jessss. I see no reason to associate this possible face with the devil, unless that's the way the devil was traditionally represented and hidden in paintings back then.

What you got against hooked noses?