Tertullian

And accordingly Elisha, having taken “wood” and cast it into that place where the iron had been submerged, forthwith it rose and swam on the surface, and the “wood” sank, which the sons of the prophets recovered. Thus they understood that the spirit of Elijah was presently conferred on him. What is more manifest than the mystery of this wood: that the obduracy of this world had been sunk in the profundity of error and is freed in baptism by the wood of Christ, that is, of his passion, in order that what had formerly perished through the tree in Adam should be restored through the tree in Christ?