The duad, with the Monad brooding behind it, is the fundamental principle of the Avesta.
A consists of two square-based pyramids turned so as to meet at their apices, and breaks up into two quartet rings and a duad.
It frankly accepts the duad as the true explanation of the actual universe.
The pillars are the same as in chlorine and its congeners, with a duad added at the base.
The duad represented the line, as being bounded by two points or monads.
Coming down nearer to our own time, we find a duad of great English poets, usually associated in our minds,—Byron and Scott.
On the hyper level the triplet becomes a duad and a unit; the duad becomes two units; and the septet a triplet and a quartet.
But the belief of Zoroaster and that of Scandinavia regard the duad as still more deeply rooted in the essence of existing things.