My Interesting Quote

I started reading a new chapter which is about the theory done by John Dalton  and the discovery of atoms. while I was reading this chapter, I found a really interesting sentence; " Neither [Dalton] nor those who followed him during the century after his work was published had direct evidence for the existence of atoms"(page 39). I found it interesting because it raised many questions in my head. For instance, I was wondering how Dalton got the idea of the existence of atoms and what made him assuming that this little thing in substances is the atom without any evidence. I'm still wondering about these things. I hope I can find an answer of those questions somewhere soon .