A brief history of atomic discoveries
Empedocles, a Greek philosopher, theorized that four elements existed in around 450 B.C.E. The four elements he theorized were Earth, Water, Fire and Air. Empedocles was incorrect about which elements existed, but he was correct in saying that elements existed, and make up everything we see. Unfortunately, Aristotle, a far more famous philosopher, had similar ideas as Empedocles, and now often gets credit for ideas he likely took from Empedocles. This is parallel to current life, where ideas are often taken without credit.
In around 400 B.C.E, a Greek philosopher named Democritus had an idea: What if everything on Earth is dividible? If it is, what is the layer you can't divide it anymore called? Democritus theorized that something called an atomos was this fundamental layer. And while what he was saying was quite broad, it was completely correct.
Pierre Gassendi was a French philosopher and Catholic priest. Before Gassendi, believing in atomism was often correlated with atheism because atomism was interpret as being soulless and meaningless, and many of the early atomic philosophers were atheist, including Democritus. This was in a time that atheism was extremely unpopular, and even often considered an insult. Gassendi changed the narrative, arguing that atomism was in fact compatible with Christianity.
In around 400 B.C.E, a Greek philosopher named Democritus had an idea: What if everything on Earth is dividible? If it is, what is the layer you can't divide it anymore called? Democritus theorized that something called an atomos was this fundamental layer. And while what he was saying was quite broad, it was completely correct.