I think Yeats is saying that the "kettle at the heel"regarding age and getting o!der is something he cannot get rid of. But that the conflict comes in when he thinks of his youth which is something he should be pulling toward but instead he is more in tune with
Plato. So Yeats probably thinks this is silly or absurd because he cannot identify with being youthful and playing with his dog. Or having a youthful mentality. So he says he chooses Plato until things change for him and until then this will be a conflict. The kettle at the
heel also reminds me of something that keeps a person indecisive or in limbo.
I hope this helps.