In mainstream Nicene Christianity, there is no restriction on kinds of animals that can be eaten.[213][214] This practice stems from Peter's vision of a sheet with animals, in which Saint Peter "sees a sheet containing animals of every description lowered from the sky."[215] Nonetheless, the New Testament does give a few guidelines about the consumption of meat, practiced by the Christian Church today; one of these is not consuming food knowingly offered to pagan idols,[216] a conviction that the early Church Fathers, such as Clement of Alexandria and Origen preached.[217] In addition, Christians traditionally bless any food before eating it with a mealtime prayer (grace), as a sign of thanking God for the meal they have.[218]