"The lamb with the lion" – often a paraphrase from Isaiah, and more closely quoted as "the lion and lamb", "a child will lead them", and the like – are an artistic and symbolic device, most generally related to peace.
The symbol is used in both Christianity and Judaism to represent the Messianic Age. In addition, in Christianity, according to a sermon by Augustine, the lion stands for Christ resurrected, the lamb for Christ's sacrifice ("He endured death as a lamb; he devoured it as a lion."—Augustine, Sermon 375A).
Isaiah 35:9 casts a lion as metaphorically forbidden in the future paradise ("No lion shall be there, nor any ravenous beast shall go up thereon, it shall not be found there; but the redeemed shall walk there"); yet, Isaiah 65:25 and 11:6–7, respectively reference such formerly ravenous beasts as becoming peaceable: "The wolf and the lamb shall feed together, the lion shall eat straw like the ox; but the serpent—its food shall be dust!"; "The wolf shall live with the lamb, the leopard shall lie down with the kid, the calf and the lion and the fatling together, and a little child shall lead them."