This is a nice text, but it's heavenly oriented to the very upper class society.
The author talk a lot about "sexual books" of the times, but you will certainly not find the "Memoirs of a Woman of Pleasure" (Fanny Hill) in the hand of a proper young woman.
(this stuff where costly rarities for men too).
It was far more simpler than this, no need for books.
Every rural girls and boys, and women and men living in a city did know, without any books,
what there is to know simply by looking at the animals in the farms
or the horses and dogs in the streets.
There was also the "education" at the wash-houses... The hubs to know everything there is to now at the time.
As for books in the 1700's over 60% of women were not literate so if one happened on one of the books it couldn't be read - but the illustrations would have been interesting to them.
I think that many of the poor lived in habitations where they all slept in one, unlit, room where they would get hints about sex from childhood.
Yeah. If anything, the 20th century was sort of a nadir for this sort of thing, as increasingly large portions of the population became more alienated from the natural world. That made it possible for young kids and teenagers to have no clear idea.
Sex and reproduction was no mystery to almost anyone historically. No doubt people, then as now, maintained various superstitions that coincidentally involved rationalizations for what they wanted to do anyway, but that's not really a matter of ignorance, so to speak. ("Come on, it's your first time, it will be OK, nothing will happen...whoops!" is not a matter of ignorance generally, but willful ignorance.)
It also covers a long time period. The period of extreme prudishness was fairly short, and happened during the Victorian era.
I have a book from the 1850s that was meant to (mis)inform on this topic. The whole masturbation makes people go blind nonsense. For people raised on this kind of book, I can believe that they would not understand sex. For people a few decades earlier, it would be a different story.
It was far more simpler than this, no need for books.
Every rural girls and boys, and women and men living in a city did know, without any books, what there is to know simply by looking at the animals in the farms or the horses and dogs in the streets.
There was also the "education" at the wash-houses... The hubs to know everything there is to now at the time.