Tradition and verse — not medical advice
When and Why
Shown in author's own English -- not a translation we made.
When I bring you coloured toys, my child, I understand why there is such a play of colours on clouds, on water, and why flowers are painted in tints--when I give coloured toys to you, my child.
When I sing to make you dance, I truly know why there is music in leaves, and why waves send their chorus of voices to the heart of the listening earth--when I sing to make you dance.
When I bring sweet things to your greedy hands, I know why there is honey in the cup of the flower, and why fruits are secretly filled with sweet juice--when I bring sweet things to your greedy hands.
When I kiss your face to make you smile, my darling, I surely understand what pleasure streams from the sky in morning light, and what delight the summer breeze brings to my body--when I kiss you to make you smile.
In plain words (ours, not the poet's): a parent says that loving and delighting their child helps them understand why the whole world is full of color, music, sweetness, and light.
Why public domain: Tagore wrote The Crescent Moon in English himself, first published London 1913. US: pre-1929 publication, public domain in the US. Tagore died 1941; public domain in India (life + 60 years) since 2002.