According to Thomas Aquinas, in the case of extraordinary Eucharistic Miracles in which the appearance of the accidents are altered, this further alteration is not considered to be transubstantiation, but is a subsequent miracle that takes place for the building up of faith. Nor does the extraordinary manifestation alter or heighten the presence of Christ in the Eucharist, as the miracle does not manifest the physical presence of Christ: "in apparitions of this sort ... the proper species flesh and blood of Christ is not seen, but a species formed miraculously either in the eyes of the viewers, or in the sacramental dimensions themselves."