Plerosis is not a disease!
"And we all, who with unveiled faces contemplate the Lord’s glory, are being transformed into his image with ever-increasing glory, which comes from the Lord, who is the Spirit." 2 Corinthians 3. 18
Plerosis is a synonym for "fulfilment". Freelance academic Sharon Jebb Smith points towards two of CS Lewis' later works, Till We Have Faces and Letters to Malcolm (the latter was published after his death) for evidence that Lewis was at least in the process of graduating from his radical asceticism (self-denial) towards a more serene relationship with God and with himself. This would certainly be consistent with his mature teaching on the primacy of love, rather than self-abnegation, as the enabling factor in our transformation into the people God has created us to become.
On account of his awareness of human frailty and the propensity we have to sin, Lewis was realistic about our not being able to reach the ultimate state of plerosis in this life, yet he seems to have become convinced of its validity as the goal to which we are drawn through faith. In Till We Have Faces, Lewis maps out two routes towards this happy estate through two fictional sisters. One is possessed of instinctive saintliness and dies young and willingly as a martyr. The other strives to emulate her more noble sister, though a life of stoical endeavour. Yet the harder she tries the drier she becomes spiritually. Resolution only comes with discovering that the route to the fulfilment (plerosis) is through love, rather than the extremes of self-seeking and/ or self-denial.
The same shift in emphasis, from asceticism to love, is apparent in Letters to Malcolm. Here prayer is presented as the essential conduit through which our rough edges and selfish preoccupations may be smoothed and redirected, as we plumb further into the depths of God's mercy and grace. Does not the season of Lent drop into our laps, as a timely opportunity to check our own progress: physically, mentally and spiritually?