Medical experimentation on humans began many centuries ago. The first “volunteers” were slaves, considered at that time to be property rather than human beings. One of the first experimenters was the famous Greek physician Herophilos (335–280 BC), co-founder of the great medical school of Alexandria and widely regarded as the “father of anatomy” (though Vesalius may argue this point). He was the first researcher to base his anatomic studies on dissection of the human body. Though this was scientifically valid and led to a greater understanding of the human body, he carried out the procedures on living slaves which raises questions about his ethics. Tertullian, a prolific Christian writer (AD 197–220) claimed that Herophilos had performed vivisections on more than 600 slaves.