Returning object to subject - called 'Returning Function to Principal' in some translations of the Ch'an Masters - should be returning 'it' (whatever it be) to potentiality. On the other hand the projection of phenomena, the sensorially-perceived universe, or objectivisation, may be said to occur via the dualistic mechanism of temporality, that is by splitting of potentiality, which is unitary, into subject and object, which then becomes a pseudo-subject 'perceiving' as negative and positive, and an intellectual interpretation of that as the projected image which is accepted as really existing.
Thus 'perceiving' itself is seen as a dual process in Time, an in-formal giving-out, taken-in as form, and then objectively interpreted. The in-formal giving-out, sometimes called 'pure perception', may perhaps be regarded as bodhi, whereas the taking-in, or normal perception and its intellectual interpretation are psycho-somatic and illusory.
The 'identity' of Form and Void in the sutras is an expression of this dual aspect of 'perceiving' - 'in-formal' articulated into 'form' by the mechanism of the skandhas and interpreted by the cognising sixth sense.
But to understand this objectively has little practical value. It must happen to us. It is happening to 'us' incessantly. It is that by which 'we' are being 'lived'. If, instead of letting it 'live' 'us', we live it - we find we are it and it is all that we are.
