308 PHYSICAL SCIENCE IN THE MIDDLE AGES. 



Divine Mind by three Triads of abstractions; and 

 in the developement of one part of this system, 

 the number seven is introduced". "The intelli- 

 gible and intellectual gods produce all things tria- 

 dically ; for the monads in these latter are divided 

 according to number ; and what the monad was in 

 the former, the number is in these latter. And the 

 intellectual gods produce all things hebdomically ; 

 for they evolve the intelligible, and at the same 

 time intellectual triads, into intellectual hebdo- 

 mads, and expand their contracted powers into 

 intellectual variety." Seven is what is called by 

 arithmeticians a prime number, that is, it cannot 

 be produced by the multiplication of other num- 

 bers. In the language of the New Platonists, the 

 number seven is said to be a virgin, and without 

 a mother, and it is therefore sacred to . Minerva. 

 The number six is a perfect number, and is con- 

 secrated to Venus. 



The relations of space were dealt with in like 

 manner, the geometrical properties being associated 

 with such physical and metaphysical notions as 

 vague thought and lively feeling could anyhow 

 connect with them. We may consider, as an ex- 

 am-pie of this 12 , Plato's opinion concerning the par- 

 ticles of the four elements. He gave to each kind 

 of particle one of the five regular solids, about 

 which the geometrical speculations of himself and 

 his pupils had been employed. The particles of 

 11 Procl. v. 3, Taylor's Translation. " Stanley, Hist. Phil. 



