The concept of the "organ" as a distinct part of the body with a specific function is a very ancient one. It's impossible to pinpoint a single discoverer.

Here's why:

* Early Civilizations: Ancient Egyptians, Greeks, and Romans all had some understanding of anatomy and organs. They dissected animals and observed human bodies, though their knowledge was limited by religious restrictions and the lack of advanced tools.

* Medieval Period: Arabic physicians like Avicenna made significant contributions to understanding organs and their functions. Their work was preserved and built upon in Europe during the Renaissance.

* Renaissance and Beyond: The Renaissance saw a surge in anatomical study, led by figures like Leonardo da Vinci and Andreas Vesalius. Vesalius, with his detailed anatomical drawings, revolutionized the study of human anatomy and contributed significantly to our understanding of organs.

Therefore, it's more accurate to say that the concept of the organ evolved over centuries, thanks to the contributions of many individuals from various cultures and time periods.