Hi Paul, everyone -
Paul, you may enjoy looking at Dzogchen, The Heart Essence of the Great Perfection, teachings given in the West by His Holiness the Dalai Lama - Foreward by Sogyal Rinpoche - SnowLion ISBN 155939-157X
"Often in the texts we find mention of the fundamental innate mind of clear light being not produced by causes and conditions. Now here it is important to understand that in general when we use the term 'produced phenomena', there are different connotations. Something can be called 'produced' because it s a production of delusions and the actions they induce. Again, it may also refer to a production by causes and conditions. And there is also a sense of 'produced' as being caused by conceptual thought processes.
Certain texts speak of the activities of the Buddha as permanent and non-produced in the sense that they are continuous, and that as long as there are sentient beings, the activities of the buddhas will remain without interruption. So, from the point of view of their continuity, these activities are sometimes called permanent. It is in the sense that this is without interruption that it is labeled permanent .
In the same manner, the fundamental innate mind of clear light in terms of its continuity, is beginingless, and also endless. This continuum will always be there , and so from that specific point of view, it is also called 'non product for it does not come into being as a result of the circumstantial interaction of causes and conditions. Rather , it is an ever -abiding continuum of mind, which is inherent within us. So from that viewpoint, it is called 'non-produced'.
However, although this is the case, we still have to maintain that because it possesses this continuity, the present fundamental innate mind - this present instant of consciousness - comes from its earlier moments. The same holds true of the wisdom of Buddha - the omniscient mind of Buddha - which perceives the two truths directly and simultaneously, and which is also a state of awareness or consciousness. Since it is a state of awareness, the factor which will eventually turn into that kind of wisdom, namely the fundamental innate nature of clear light, will also have to be maintained to be a state of awareness. For it is impossible for anything which is not by nature awareness to turn into a state of awareness. So from the second point of view, the fundamental innate mind of clear light, is causally produced."
Shantideva - Wisdom Chapter -
more on Buddhahood and Buddha-nature by His Holiness the Dalai Lama.