The "midst" of something in the Bible represents the thing that is most central and most important to the spiritual state being described, the motivation that drives everything else. In general this will be something we love or feel, because at the core of things we are what we love; our loves define us.

(References: Apocalypse Revealed 44, 90, 268; Arcana Coelestia 2252, 2940, 10153, 10365, 10557, 10635, 10641)

“Life” in the Bible has reference to what we love, to our affections, because what we care

about actually makes us who we are. “Light” has to do with our thinking, our intellect –

which is not life itself, but defines and guides our lives. This verse, then, in saying “in

him was life,” reveals that it is divine truth that inspires our feelings, that makes us want

what is good. And when we want what is good, that will be “the light of men,” inspiring

us to seek and understand true ideas that can help us actually be good and do what is

good.

So divine truth – the exquisite expression of the Lord’s love – is not only the driving

force behind creation, it is also the agent that creates our own internal lives, inspiring our

desires for good and through them our understanding of what is true.

(References: Apocalypse Revealed 200; Arcana Coelestia 2894, 4687 [2-3]; Teachings about the Lord 1; True Christian Religion 39)