Moses de Leon, Mishkan ha-Edut, MS Berlin Or. Quat. 833, fol. 35a.

Jewish Mysticism
I have seen in the secrets of Torah a deep matter concerning the verse “And all the people saw the voices,” the secret of the speculum that does not shine [i.e., Shekhinah]. They said that this speculum is hidden and takes form. She stands and is momentarily seen, then returns and is hidden as at first; she takes form and afterwards is hidden and removed. This is the hidden secret of the verse, “all the people are seeing,” we-khol ha-‘am ro’im. It is written ro’im [in the present tense] and not ra’u [in the past tense].