For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some 'organic element' since I couldn't accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
Blows my mind how this by its bare bones is just simple statistics and combinations but is a totally different story when described in English. I'm sure there are similar facts like this that are mathematically logical but to a layman is confusing and inconceivable.
communism