Why can such drastic changes occur merely because of a physical change, if "who we are" resides primarily in the soul?
I think you need to take the question back one step and ask "who are we really
?". Is my soul simply the collection of memories which make up the "story" of "who I am"? Or is it something else
Two things make me believe it's "something else". The first is the fact that the Church Baptises and Communes pre-verbal infants. I can't remember
my Baptism and first Communion, yet the Church received me as a full member even when my cognition and self-awareness hadn't even developed. I didn't even know that my hands and toes "belonged to me" when I became a member of the Church, so clearly, self-awareness is not considered an essential element of the Soul by the Church.
The second thing which makes me believe that the soul is something other than the cognitive function of the brain is my own experiences. For example, as I get older, I am experiencing Peak Experiences and Ecstatic States
with increasing frequency. When I experience these states, the "normal" cognitive function of my brain doesn't seem to be involved at all. I seem to be experiencing very real things through direct, non-verbal experience- "inexpressible words, which it is not lawful for a man to utter
" (2Corinthians 12:4). In such states, knowledge and prayer becomes non-verbal, non-emotive and history becomes irrelevant, or rather secondary to the Ultimate Reality which binds all things together.
As a psychologist with a particular interest in neuroscience and who works in the field of abnormal psychology- dealing with psychosis, mood disorders etc., these Peak Experiences and Ecstasies are something I've studied and thought about. They are not experiences of depersonalisation, derealisation or dissociation, and I know this because I have experienced the former two through experimenting with cannabis use in my youth and the latter I have experienced as a result of Post Traumatic Stress Disorder in my twenties. The Peak Experiences I'm experiencing are vastly different to these, and the only language I have been able to find (with the help of my Spiritual Father) which comes close to describing them is the notion of the "nous" as "the eye of the soul" directly apprehending the logoi
of created things, and the Eternal Logos Who contains them all as described in the Philokalia
So now, when I look at Gwen, whose dementia has now progressed to the point where she has to be fed and she no longer recognises her own family, I don't despair that "she is no longer there" as some of her family do. She is
there, and I know this because in one of my Peak Experiences, we met in that other, more real Reality. And interestingly, I am now the only person she recognises when I visit her in her dementia.
My conclusion: The soul is real, it is who we really
are, and for the most part, our everyday notions of "who we are" are just illusions.