Can Anyone Advise Us on the Origin of the Yiddish Phrase “Touching a Wall”?

Isi Unikowski has this query:

My father has always used a peculiar Yiddish expression to refer to living in straitened circumstances, such as when, as a backpacker, I stayed in particularly down-at-heel lodgings in London, or as a warning to my brother and me about some dubious living or work arrangements. This was “Du vest tapn a vant,” literally, “You’ll be touching a wall.”

Can you shed any light on where this expression comes from?

Although the Yiddish verb tapn, which is a cognate of English “tap,” can mean to touch, Du vest tapn a vant is better translated as “You’ll be groping a wall.” The expression refers to undertaking something that has little chance of success, and it may have originated in the image of vainly running one’s hands over a wall in search of a foothold or handhold to help one climb it. This would make it akin to the Yiddish idiom gey krikh af di glaykhe vent, “Go climb smooth walls.”