Preposition
at the door of
(idiomatic) Very near to; such that something is imminent.
Synonyms: on the brink of, on the point of, on the verge of
I have always knocked at the door of that wonderful and terrible enigma which is life. Eugenio Montale
At the door of every happy person there should be a man with a hammer whose knock would serve as a constant reminder of the existence of unfortunate people. Anton Chekhov
You knock at the door of Reality. You shake your thought wings, loosen your shoulders, and open. Rumi
It is useless to knock at the door of a deaf man. Greek Proverb
Every dog is a great barker at the door of his own house. Arabic Proverb
Every fault is laid at the door of the hyena, but it does not steal a bale of cloth. Hausa Proverb