William Harvey and René Descartes famously disagreed in their accounts of what the heart is doing as it gives its characteristic beat. Both authors recognize that the heart alternates between squeezing and opening up. Harvey posits that the beat occurs as the heart squeezes closed while Descartes believes the beat happens as the heart opens up. Both have access to similar observations. How is it that they come to opposite conclusions? I’ll discuss how their differing views of how to think about living things likely play a role in this disagreement. I'll examine what we have learned since their time about how the heart beats. Finally, given what we’ve learned, I'll ask the question: What can we say about the nature of living things?