Projecting for three next decades birth rate and death rate modern lines, INSEE has shown recently that since 2030 death rate will concern first of all generations "bebi-boom", and the quantity of death will surpass quantity of newborns. Natural balance (an increase in population at the expense of aboriginals, - a comment of recentury) Which relative density is rather considerable today, will thaw, as snow on the sun, and immigration as it already occurs at our neighbours becomes a determinative of growth of the population. However anybody from participants of today's debate does not warn us about it. I in the book consider two opposite hypotheses accurately to designate problem borders. Imagine, first of all, that thanks to regulation France reduces twice the natural balance and instead of 100 thousand persons grows on 50 thousand annually. It will delay all for five years the fatal moment when immigration becomes the leading factor of growth of the population. The policy of the control over streams cannot prevent such succession of events. In a demography not all is possible.