So, in the seventeenth century book* I couldn’t talk about ‘reproduction’ because it wasn’t a seventeenth century term — people talked about ‘generation.’ That is what we would call ‘reproduction’ and ‘development’ rolled together in one word. Similarly, you can’t talk about heredity before the 19th century. Heredity only takes on a biological meaning in the 1830s — people didn’t have a word to describe the relationship between parents and offspring. Then you realise that there’s a reason why people can’t see things — they don’t have the words, the ideas. The concepts aren’t there and therefore you can’t think them.
I was very fortunate and lived for 18 years in Paris. I went with absolutely awful French and ended up pretty much bilingual. One of the things I realised is that when you can speak another language, you can think things you can’t think in your mother tongue. Words and thoughts are interconnected. That’s one thing that I tried to bring over in my books, by trying to look at what people thought at different times and how the ideas and concepts either limited them or finally enabled them to understand things in a richer way.
* The Egg and Sperm Race: The Seventeenth-Century Scientists Who Unravelled the Secrets of Sex, Life and Growth