In tenth-century Iraq, a group of Arab intellectuals and scholars known as the Ikhwan al-Safa began to make their intellectual mark on the society around them. A mysterious organisation, the identities of its members have never been clear. But its contribution to the intellectual thought, philosophy, art and culture of the era - and indeed subsequent ones - is evident. In the visual arts, for example, Hamdouni Alami argues that the theory of human proportions which the Ikwan al-Safa propounded (something very similar to those of da Vinci), helped shape the evolution of the philosophy of...