To put the cart before the horse means to get the order of things reversed, as to give the answer to a riddle while attempting to give the riddle.
This common occurrence must also have been common among the ancient Greeks and Romans, for they also had sayings that agree with ours.
The Greeks said, “Hysteron proteron,” which meant, literally, the latter the former. The Romans said, “Currus bovem trahit przpostere,” or, literally, the plow is drawn by the oxen in reversed position, and this, as a matter of record, is the way the saying first appeared in English.
It is found in Dan Michel’s Ayenbite of Inerwyt (Remorse of Conscience), a translation by Dan Michel of a French treatise, written by Laurentius Gallus, in 1279, into the dialect of Kent. Michel renders it “Moche uolk of religion zetteth the zouly be-uore the oksen, (Many religious folk set the plow before the oxen).”
In the course of the next two hundred years the English version became the present usage.
It must be recalled, of course, as the artist has shown, that some coal mines, cut as tunnels, are so laid out that a coal cart, when filled, could go by gravity out to the open, the horse or mule being needed chiefly to get the empty cart back to the face of the mine.
But actually, on the outward trip, the horse is reversed in its shafts to act as a holdback, keeping the full cart from going too rapidly.