You parents. You professors. You prudes. This is addressed to you. What have you got to say about it? You have tremblingly closed the question. I would coolly open it. You have rebuked God by silence. I would praise God by speech. II THE ARGUMENT AND THE INFORMATION No apology is offered for what is said in the following pages, but a brief explanation is virtually necessary to make clear, from the outset, the reasons why it has been written. It is one of the chief characteristics of the human race that the knowledge acquired by one generation can be passed on to the generations that follow; and that, in this way, progress in the betterment of life's results and the adaptation of means to ends can make a steady and reliable advance. Such a method of evolution and growth is not possible in the vegetable or animal kingdom, where _instinct_ is the only means for the transmission of acquired knowledge. It is this feature that differentiates man from all other created beings. But here is a curious fact: In one realm of human experiences, in all Christian civilized countries, it has been considered wrong, even in some cases being counted a criminal offense, punishable by fine and imprisonment, for anyone to make any record of, or transmit to anyone else, any knowledge that may have been acquired regarding sex relations in the human family. To be sure, there has been preserved, from time to time, a body of _professional_ knowledge of this sort, made and prepared by physicians, but _confined strictly to that class of people_. No attempt has been made to disseminate such knowledge among those who most need it--the common people. On the contrary, every possible effort is put forth to keep such knowledge from them. This is wholly at variance with the practice regarding all other forms of human knowledge, which is to spread, as widely as possible, all known data that have so far been obtained. There is not space, in this small volume, for pointing out the reasons for this anomalous condition of affairs, but the chief cause of its status, past and present, is grounded on two sources: The first of these is a brutal selfishness which has come over to modern times from a savage past; the second is a sort of pious prudery. The result of these causes has been to make the whole subject of sex in the human family, with its functions and mission in human affairs, together with its proper training, discipline and exercise--to make all these things _tabu_, something to be ashamed of and ignored as much as possible, and all the knowledge regarding them that one generation has been permitted to transmit to those who come after, may be summed up in these words, namely "_Thou shalt not_."