Water is an essential part of the rituals as- sociated with Islam and thus the pool is not only an essential part of the mosque, but also, by derivation, an essential part of any living area or garden. Within the mosque its simplest expression is the square pool found in the centre of the meidan or square which forms the centrepiece of most Persian mosques. The 14th century Masjed-e-Ali in Isfahan is a typical exaple of this. The pool set within the four interior walls of the mosque with the four eivans or porches reflecting into it makes it a central part of the mosque and, as it were, concentrates the religious energy of the building into it. The pool thus becomes both a mirror of the self through its use in ablution and a mirror of God through its reflection of the four quarters, in particular, of course the porch which faces in the direction of Meccah.
The diagram at the top has been adapted from one in "The Sense of Unity" by Nader Ardelan and Laleh Bakhtiari published by Chicago University Press