II INTERVENTIONS UPON HUMAN PROCREATION 

By "artificial procreation" or " artificial fertilization" are understood here the different technical procedures directed towards obtaining a human conception in a manner other than the sexual union of man and woman. This Instruction deals with fertilization of an ovum in a test-tube (in vitro fertilization) and artificial insemination through transfer into the woman's genital tracts of previously collected sperm. 

A preliminary point for the moral evaluation of such technical procedures is constituted by the consideration of the circumstances and consequences which those procedures involve in relation to the respect due the human embryo. Development of the practice of in vitro fertilization has required innumerable fertilizations and destructions of human embryos. Even today, the usual practice presupposes a hyperovulation on the part of the woman: a number of ova are withdrawn, fertilized and then cultivated in vitro for some days. Usually not all are transferred into the genital tracts of the woman; some embryos, generally called "spare ", are destroyed or frozen. On occasion, some of the implanted embryos are sacrificed for various eugenic, economic or psychological reasons. Such deliberate destruction of human beings or their utilization for different purposes to the detriment of their integrity and life is contrary to the doctrine on procured abortion already recalled. The connection between in vitro fertilization and the voluntary destruction of human embryos occurs too often. This is significant: through these procedures, with apparently contrary purposes, life and death are subjected to the decision of man, who thus sets himself up as the giver of life and death by decree. This dynamic of violence and domination may remain unnoticed by those very individuals who, in wishing to utilize this procedure, become subject to it themselves. The facts recorded and the cold logic which links them must be taken into consideration for a moral judgment on IVF and ET (in vitro fertilization and embryo transfer): the abortion-mentality which has made this procedure possible thus leads, whether one wants it or not, to man's domination over the life and death of his fellow human beings and can lead to a system of radical eugenics. 

Nevertheless, such abuses do not exempt one from a further and thorough ethical study of the techniques of artificial procreation considered in themselves, abstracting as far as possible from the destruction of embryos produced in vitro. The present Instruction will therefore take into consideration in the first place the problems posed by heterologous artificial fertilization (II, 1-3), ^* and subsequently those linked with homologous artificial fertilization (II, 4-6 ) .^** Before formulating an ethical judgment on each of these procedures, the principles and values which determine the moral evaluation of each of them will be considered. 

A. HETEROLOGOUS ARTIFICIAL FERTILIZATION