Guido da Siena was the all but mythical founder of the Sienese School. He signed a picture in the Palazzo Pubblico, Siena, and dated it 1221, but there are other pictures, also in Siena, associable with him which are datable 1262 and in the 1270s. There are therefore two schools of thought: (i) that 1221 is correct, in spite of the evidently repainted surface of much of the picture. In this case (a) Siena precedes Florence in the development of Dugento painting, and (b) the other pictures mentioned are by Guido's followers, not by Guido himself. (ii) The other school (which contains few Sienese) holds that 1221 is an old tampering with an original date c.1261 - perhaps MCCXXI was altered from MCCLXI - and the other pictures are therefore his and contemporary. Recent X-rays give no grounds for believing this. Another theory, more reasonable, assumed that the picture was painted perhaps 1260/70, but was a copy and replacement of an older image, and the date 1221 was copied faithfully from this older image. //