SENTENCE USAGE: "Them nincompoops in Washington, D.C., are talkin’ about raisin’ taxes again! Don’t that bunch of leeches know we ain’t got no money? You can’t get blood from a turnip!"
How does one expect to get blood from a vegetable?
This old idiom means: You cannot get something from a person, especially money, they don’t have. You can only get what people are willing or able to give. A turnip cannot be coaxed, squeezed or cajoled into producing blood. All efforts at obtaining blood from this vegetable will be futile.
Some believe it is a statement referring originally to the difference in sacrifices made in Genesis 4 by Cain and Abel. Abel kept flocks (a shepherd/rancher) and Cain worked the soil (a farmer/row cropper). In the course of time, Cain brought some of the fruits of the soil as an offering to the Lord (maybe had a turnip or two thrown in the basket). But Abel sacrificed the firstborn of his flock and brought it as an offering (a meat offering requiring bloodshed). The Lord looked with favor on Abel and his offering, but on Cain and his offering he did not look with favor. In the Old Testament, God required a blood offering for sin.
Hence, you can’t get blood out of a turnip.