Before going to the central theme it is perhaps necessary to say what science is, as opposed to other human knowledge. In a rather short statement science may be defined as a world picture, or it may be closer to the heart of the matter if it is said that science is the product of organized fantasy about the real world. Up to this point it must be hastily added that there are also many other branches in human knowledge that share the same characteristics with science. For example, experiment is thought to be peculiar to science. Actually the alchemists of the middle ages did undertake experiments. What was missing in their experiments -and only later applied by Lavoisier and other giants of science in that period- are the hypothetical-deduction methods that science multiplied. Again, observations and logic were also thought to be peculiar to science. We learned, however, the astrologers did make observations and that theologians had logic and that logic is is perhaps the most methodological component of all human inquiry. Thus, as such, one would not be able to discern science from the rest of human activities. But there are boundaries within which science can legitimately operate. The first one is that science denies two types of truth: truth by logic and truth by faith. On the other hand science accommodates only one truth. The other boundary is the constant test by internal logic of necessity and by external public record. These boundary conditions must always be observed, as otherwise one will fall into the realm of magic.