His name stands tall among scientists who took the brave step to defy their religious leaders and look into things for themselves. The Christian faith had long professed that the heart was the soul and that the earth was the center of the universe. They also taught that the dead can feel and that heaven and hell are places of extreme benevolence and beauty or of eternal suffering. In the superstitious world of the past these things were cemented in the psyche.
What da Vinci discovered by dissecting bodies and looking into the vascular system is that the heart is the pump that makes the blood circulate. He also discovered nerves and this caused furore among the church hierarchy. It meant that stimulus applied to any part of the body was carried as messages to the brain via the nerves and that without them people simply cannot feel anything.
The threat to the establishment was huge. It survived on brainwashing people into accepting that heaven and hell are real places and that the faithful will go to the former while the recalcitrant will end up in the latter. The church had so much power that anything that opposed it was instantly condemned and people like scientists could be burned as witches. Fortunately Leonardo fled to France to escape such a fate.
The greatest weapons of faith are heaven and hell and the Catholic Church claims to hold the keys to them. It has built a huge organisation with the power they provided but it is time for them to go.
Most people today know that nerves are important to feel and that the dead have no living nerves. There is also no sign of heaven or hell anywhere so they cannot exist as they have no presence. The work of Leonardo da Vinci is still influencing the world today and his contribution to science and particularly to an understanding of how the body works is a major part of it.