Preparations to be certain the angel is "on the level." It and "on the beam" are interesting expressions. When my father was in radioman's school during WWII, his letters home were peppered with "on the beam," which I always assumed had something to do with either a balance beam or a construction beam. It's neither - the expression comes from an aircraft homing in on a radio navigation beam, akin to someone being "on the right track."
I didn't hear him use "on the beam" much when I was a kid, but he used "on the level" all the time."On the level" isn't really related, but means honest or straightforward. One can imagine Jesus saying of Nathaniel, "He's on the level." So was my father.