Where did St. Thomas Aquinas say Mary approached the borders of the Hypostatic Union?

Question

Where did St. Thomas Aquinas say Mary approached the borders/fringes of the divinity or Hypostatic Union?

Answer 1

The closest I've been able to find, his sermon On the Angelic Salutation (Lent 1273):

She Herself [was] more holy than anyone after Christ.
_{Ipsa (Virgo) [fuit] magis quam alius sanctus, praeter Christum.}