False also and harmful to Christian education is the so-called method of "coeducation." This too is founded upon Naturalism and the denial of original sin by many of its supporters. But all are based upon a deplorable confusion of ideas that mistakes a leveling promiscuity and equality with the legitimate association of the sexes.

 The Creator has ordained and disposed perfect union of the sexes only in matrimony, and with varying degrees of contact, in the family and in society. Further, there is nothing in nature itself, which fashions the two quite different in body, temperament and abilities, to suggest that there can be or ought to be promiscuity, and much less equality, in the training of the two sexes. These, in keeping with the wonderful designs of the Creator, are destined to complement each other in the family and in society precisely because of their differences, which therefore ought to be maintained and encouraged during the years of formation, with the necessary distinction and corresponding separation, according to age and circuмstances.

 These principles, with due regard to time and place, must, in accordance with Christian prudence, be applied to all schools, particularly in the most delicate and decisive period of formation, that is, namely, the period of adolescence. And in gymnastic exercises and sports, special care must be had of Christian modesty in young women and girls, which is so gravely impaired by any kind of exhibition in public.

 Recalling the terrible words of the Divine Master: "Woe to the world because of scandals!"[Vae mundo a scandalis! Matt., 18: 7] We most earnestly appeal to your solicitude and your watchfulness, Venerable Brethren, against these pernicious errors, which, to the immense harm of youth, are spreading far and wide among Christian peoples.