It is truly amazing how the years, which seem like nothing, which pass imperceptibly, disfigure reality to a point where there is not a single remnant left of what once was. So close one century to the other, and sometimes so disparate as to be unrecognizable. Anyone who makes a thorough analysis of the customs of past eras will be amazed, to the same extent as if someone from the past could catch a glimpse of the future. In both cases, a mixture of strangeness, repulsion, incomprehension and astonishment. Astonishment because, in theory, the human species has always consisted of men. However, for sociology, it is possible to describe men from different times as distinct species.