see with half an eye

see with half an eye

To be able to see, notice, or understand something as being plainly obvious or true. Anyone with even a cursory knowledge of the reason can see with half an eye that such a conflict was inevitable. Tom, everyone sees with half an eye that you're having an affair—it's only a matter of time before Michael figures it out, too.
See also: eye, half, see

see with half an eye

Notice the obvious, tell at a glance, as in I could see with half an eye that he was sleeping through the entire concert. This hyperbolic expression, which presumably alludes to an eye that is only half-open, was first recorded in 1579.
See also: eye, half, see