US-P16.033ab ।US-P16.033cd ॥
In plain words
If that non-duality is recognized as existing prior to all mental projections of being and non-being, it is because of its uniform nature; it is eternal and entirely apart from what is imagined.
Close to the Sanskrit
If prior to the mental construction 'existent, non-existent, existent and non-existent thus', that non-duality is acknowledged on account of uniformity, but it is eternal and other than the constructed.