My first reading of this poem was very literal. I imagined Emily watching over an infant sleeping in it’s crib which was outside under the shade of a tree. As she approached the crib and saw the child sleeping she gently placed her foot on the crib to rock it, but upon recognizing that she was being rocked, woke up and, flushed with crimson (“Carmine”) and began to cry.
However, while that is one way to read it, as I researched this poem I learned that Emily might actually be talking about a flower whose location only she knows. When Emily goes out to the tree under which this flower grows, the flowers hears her footsteps (“She recognized the foot”) and pops out of the ground in full crimson (“Carmine”) bloom. Emily this exclaims “And see”! (exclamation point mine for emphasis) as one would out of pure delight to discover something so wonderful happening right before them.
Yet she could also be writing about remembering a pleasant memory which brings her joy, or perhaps drawing a pleasant reaction out of a friend who has been sad or ill, and when the friend hears Emily’s footsteps it brings them both pleasure.
In each case, however, Emily is the one making the first movements. The flower / child / memory “slept” but as Emily comes along “mute” she awakens what was previously dormant and a joy is brought into the world, “And see”. One could then read this as her poetry silently coming up to us and awakening inside us a pure joy at discovering something so beautiful and thus we both share in the act: she creates the art silently and the joy is born inside the reader, “And see”.