Perhaps a wider look at T. S. Eliot's "Rhapsody on a Windy Night" may enable us to gain a deeper understanding of the evident aspects of the quote. Essentially, in the fourth stanza, the persona articulates
“the hand of a child, automatic, slipped out and pocketed a toy… I could see nothing behind that child’s eye.” Here, Eliot illustrates a homeless child who, like the woman, has been desensitised to his surroundings as suggested by his lack of emotion in what is normally perceived as an act of youthful anticipation.
The synecdoche in
“nothing behind that child’s eye” implies the absence of their soul or humanity, the depersonalisation of the lost child reflecting the sullen apprehension of the early twentieth century. Hence, through experimentation with textual form, Eliot highlights the alienation of humanity in a world dislocated from security and certainty.
I hope this helps!