For imagination generally, and spiritual or meditative experience in particular, to provide real, objective, valid knowledge and guidance - there needs to be some explanation of why.
Where, in particular, does this knowledge and guidance come from; why should this be 'within' us, and and why should it be valid?
My answer is that it comes from the Heart, and (to put matters bluntly and simplistically) The Heart is made of two things - our eternal selves and a piece of God.
Since these are eternal and God is divine, they may, in principle, provide valid and true guidance.
Ideally these two things should be in perfect harmony, in practice the essential self may dissociate itself from God and go against God - and we call that pride - or some people call it original sin, because it is structural.
I have been writing for some time on the importance of The Heart in discernment - for example:
I think I can now say a bit more about how the Heart may be conceptualized - and just 'what it is' that we consult when we look within ourselves for guidance.
First, it seems clear that The Heart is within us - this is not a matter of tuning-into some external guidance.
So, what could be within us that is capable of guiding us?
I put forward a metaphysical schema which seems to me to account for things and lead to acceptable inferences:
This scheme has it that within each person is an unique individual essence (what I called an eternal flame of agency); and also a divine flame - it could be expressed as a piece of God-within-us.
I propose that these two eternal essences are what is consulted when we look within ourselves to make a discernment of The Heart.
The objective validity of the knowledge and judgement of The Heart comes from the fact that these are eternal in origin.
But these are two things. Theosis, the becoming divine (Sons of God) which is the great task of each one of us, is about our essential selves and God coming into harmony, into communion, into perfect accord; but the problem is that we can (and often do) distinguish our 'selves' from God, and increase that distinction (instead of diminishing it) by following the discernment of the self and not that of God-within-us.
The fact that this distinction is possible could be termed original sin, because it is built-in - our temptation to do act of separation could also be original sin because it is gratifying in the short term.
The subjective feeling of 'pride' is the name for this gratification - our pride is at being able to discern what God wants, and then NOT doing it - pride is the gratification of defying our creator.
Anyway, this is what seems to be meant by The Heart - these eternal things within us: the essential pre-mortal self, and a piece, shard, fragment or little flame of and from God.
Something of the sort explains why The Heart can be our guide - indeed should be our guide; and also explains why it can all go terribly wrong: when we consult our Heart but choose to obey the discernment of our Self even when, or especially when, the Self is in defiance of God-within-us.