The problem of the homosexual cannot however be avoided in this way, for the simple reason that the invert forms so comparatively large and permanent a part of the community. It is difficult to attempt an accurate estimate, partly because many homosexuals are so afraid of incurring the odium of public opinion that they successfully disguise their true nature and are unsuspected even by their most intimate friends. But there is a more fundamental difficulty. It appears to be undeniable that a large number of normal people possess to some extent a strain of the homosexual temperament. We have, in fact, as in almost all classifications, not a naturally dividing gulf but a gradually ascending scale. Some individuals may have only 5 per cent. inverted and 95 per cent. hetero-sexual tendencies, while others are only 10 per cent. normal. There are a large and increasing number of persons who are almost equally balanced on either side. These bisexuals often marry happily and at the same time enjoy homogenic experiences. When we remember that, according to psycho-analysis, everyone about the age of puberty passes through a homosexual stage, it is probably not an exaggeration to state that few people fail to preserve a stratum of this nature, however small the percentage and however deeply such tendencies may be buried in the unconsciousness. If however we decide to draw an arbitrary distinction and to define persons with less than 30 per cent. inverted nature as normal, persons from 30 to 60 per cent. as bisexual, and the remainder as homosexual, we are left with a considerable number of the last variety. Havelock Ellis has reckoned the percentage of homosexuals among the professional middle classes in England as 5 per cent. and among women as 10 per cent.[17] In any case the popular view that the proportion is so small as to be negligible is quite impossible, and is due to the fact that most men are so unobservant of psychological evidence that their opinion is of little serious value.