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.
Also when the leap years were introduced, the priests (who were to take care of the calendar) didn’t understand what dis “every four years” mean, and used to put a leap year every three years.
And the Lord spake, saying, “First shalt thou take out the Holy Pin. Then shalt thou count to four, no more, no less. Four shall be the number thou shalt count, and the number of the counting shall be four. Five shalt thou not count, neither count thou three, excepting that thou then proceed to four. Six is right out. Once the number four, being the fourth number, be reached, then lobbest thou thy Holy Hand Grenade of Antioch towards thy foe, who, being naughty in My sight, shall snuff it.”