In the first few lines of Burnt Norton, Eliot was being completely and baldly literal: 'If all time is eternally present then...' It is dry philosophical stuff, and I think unpacking the meaning is not doing any violence to the robust text.
In the remaining lines of the first stanza - about the rose garden - he speaks obliquely or metaphorically. There are massive problems - don't think I don't know - with unpacking that imagery. Some people - and I think espresso_addict took this view - would say that the overt meaning - a man going into a garden - is the right thing to concentrate on. And that may be true, because that overt narrative is what is consciously articulated or chosen by the poet. Perhaps I should leave the unarticulated alone, let it operate on the subconscious, without being hauled into daylight. Also, very commonly, people say that articulating implied meaning is destructive or demeaning, and poetry should be talked about in terms of its formal characteristics (or whatever - things other than 'what it means').
But I have found that trying to put implicit meaning into words has made the poem richer for me, and that is why I am sharing it as I do it. Trying to articulate something I felt without words forces me to join up the verbal and non-verbal parts of my mind and for me that is pleasurable. I don't know how common that is.
And I do believe without any real doubt that in talking about the rose garden and our first world, Eliot is referring to the Fall and our lost innocence. Or no - no, let me put it like this - he is making a poem about a tragic paradox of human consciousness which is also dramatised in a Biblical story and in various other stories and personal experiences.
The lines about ghosts of children and leaves and formal structures are about a way of living with that tragedy: he is saying the same thing as Yeats said in the lines 'How but in custom and in ceremony/ Are innocence and beauty born?' I think this second reading of the rose garden section is less solidly compelling, and furthermore Eliot presents this way of being - ceremonial calm as a way of suspending our grief and loss - as a transient or failed strategy, in the next lines, which I will put in another post.