I was inspired by the legend of wounded Fisher King in search of healing and the wasteland which cannot flourish unless the King is healed.
The lake represents an "otherworld" where time and the usual pressures of life have no meaning. Tolkien's Lothlorien is an example of such a place.
You can read more about the myths here
Lakes were an important part of Celtic mythology.For example in the King Arthur legends,he is given his sword by the Lady of the Lake and taken acros a lake to be healed after his last battle.
I often think of my favourite operas when I write and I had the music of Wotan and Bruennhilde's embrace from Act 3 of "Die Walkuere" in my mind when I wrote Aragorn and Faramir's reconcilliation.
The Grail realm in Wagner's "Parsifal" also helped inspire certain scenes.
Aragorn and Faramir's experience of oneness with all is best summed up in the Sanskrit phase "Tat Twam Asi" which is fully explained here,
The story also contains other spiritual themes which will further unfold as the story unravels.