Quote from the Hermetica:

Atum is the Whole

which contains everything.

 He is One, not two.

He is All, not many.

 The All is not many separate things,

 but the Oneness that subsumes the parts.

 The All and the One are identical.

You think that things are many

 when you view them as separate

but when you see they all hang on the One,

 and which flow from the One,

 you will realise they are united -

  linked together,

 and connected by a chain of Being

 from the highest to the lowest,

 all subject to the will of Atum

 The Cosmos is one as the sun is one

, The moon is one and the Earth is one.

 Do you think there are many Gods?

 That's absurd - God is one.

 Atum alone is the Creator

 Of all that is immortal,

 And all that is mutable.

 If that seems incredible, just consider yourself.

 You see, speak, hear, touch,

 Taste, walk, think and breathe.

 It is not a different you

 Who does these various things,

 But one being who does them all.