The child is father to the man

What does the phrase "the child is father to the man" imply?

Gerard Manley Hopkins (1844-89). Poems. 1918.
68. 'The child is father to the man'
'THE CHILD is father to the man.'
How can he be? The words are wild.
Suck any sense from that who can:
'The child is father to the man.'
No; what the poet did write ran, 5
'The man is father to the child.'
'The child is father to the man!'
How can he be? The words are wild.