VII: 4

Chapter 7, Verse 4

"Earth, fire, water, wind, ether,
Mind, the discerning faculty
And the sense of 'I':
These are the eight aspects of Nature."

Father Bede Griffiths:

These are the eight constituents (Tattvas) of Nature (Prakriti).  Beyond the five material elements, the ether being a sort of bridge to the immaterial, are the three constituents of human nature:  the recording faculty of the mind (Manas), the intuitive intelligence (Buddhi) and the ego, or sense of "I" (Ahongkara).

Sri Krishna Prem:

Before students can comprehend the supreme unity, they need to understand the twofold aspect of the manifested Universe.  In all that is manifested, whether gross or subtle, whether living beings or what we call "dead" matter, there are the ever-changing forms and the underlying power which supports them.  Whether these are the forms of matter made up of the five elements, or the more subtle forms of thought, all form is but a transient play that is upheld by the higher, living power in the light of consciousness.