Aristotle, Galen, and Hipparchus | The history of science not only traces the journey of humanity’s knowledge and exploration but also sheds light on the lives and works of individuals who pioneered this journey. Figures such as Aristotle, Galen, and Hipparchus, who lived in the ancient times, are thinkers who laid the foundations of science and formed the basis for many modern concepts.
Aristotle (384-322 BC)
Aristotle (384-322 BC), one of the most influential philosophers of the ancient Greek world, stood out as a scientist with profound thoughts in natural philosophy, logic, politics, and many other fields. After receiving education as a student of the renowned philosopher Plato, he established his own school, the Lyceum, and made significant contributions in various fields.
Aristotle’s approaches in logic and theory of knowledge left lasting impacts on Western thought. His distinction between “first causality” and “second causality” became a fundamental building block in philosophical thinking. First causality refers to the most fundamental reason that constitutes the cause of an event, while second causality represents more indirect causes of an event. This distinction formed the foundation of Western thought and became an important tool for understanding cause-and-effect relationships.
As a natural philosopher, Aristotle conducted meticulous observations on the classification, anatomy, and behaviors of plants and animals. His work “The Nature of Species” is one of the first comprehensive works that deals with the classification and characteristics of plants and animals. Additionally, in his work “On the Heavens,” he proposed the theory of “celestial motions” to explain the movements of celestial bodies. This theory is considered a significant step in interpreting the movements of planets and stars.
Aristotle’s contributions have left profound traces not only in the ancient Greek world but also in the evolution of Western thought. His work in logic, theory of knowledge, biology, and astronomy has made him one of the cornerstones of science. Aristotle’s ideas and approaches have made significant contributions to the development of scientific methodology and the evolution of philosophical thought.

Galen (129-200 AD)
Galen (129-200 AD), who lived during the ancient Roman period, is recognized as a prominent physician who had a significant impact on the field of medicine. Building upon the teachings of the ancient Greek physician Hippocrates, Galen made lasting contributions to the field of medicine. His meticulous approach to studying the functioning of the human body and diseases marked a significant milestone in the history of medicine.
His anatomical studies and theories explaining the causes of diseases became foundational principles in the field of medicine from the Middle Ages to the Renaissance. Galen believed that diseases stemmed from imbalances in the body and proposed treatments to restore this balance. This theoretical approach influenced medical practice for centuries and was used to explain the fundamental causes of diseases.
One of Galen’s most significant contributions was the concept of the balance of the four basic humoral fluids (blood, phlegm, yellow bile, black bile) in the body. According to this theory, human health and diseases were closely related to the balance of these fluids. According to this theory, the causes of diseases were imbalances in these fluids, and the main point of treatment was to restore this balance. This concept greatly influenced medical practice and guided the thought structure in the field of medicine for centuries.
Furthermore, Galen’s contributions to anatomy played a crucial role in the advancement of medical science. Despite the limited knowledge of his time, he made important observations about the structure and functioning of the human body, especially regarding the muscular and organ systems. This anatomical knowledge laid the foundation for the development of the field of medicine from the Middle Ages onward.
Galen’s contributions to the field of medicine were not only impactful during his time but also continued to be influential in the centuries that followed. His anatomical studies, the concept of humoral balance, and theories explaining the causes of diseases are considered fundamental elements in the field of medical science. Galen’s ideas have shaped medical practice from the Middle Ages to the Renaissance and have left a significant legacy that continues to promote scientific progress.

Hipparchus (190-120 BC)
Hipparchus (190-120 BC), a pioneer in the field of astronomy during the ancient Greek period, conducted important studies in observational and computational astronomy. His studies on the movements and positions of celestial bodies had revolutionary effects both in his time and for future generations in the field of astronomy.
One of Hipparchus’s most notable contributions was creating the first star catalog by systematically classifying the brightness of stars. This catalog provided significant information about the positions and brightness of stars in the sky, laying the foundation for future observations. Additionally, this catalog enabled the systematic tracking of changes and movements in the brightness of stars.
Hipparchus is also credited with laying the foundations of trigonometry. These foundational elements of trigonometry played a crucial role in calculating the positions of celestial objects. By using trigonometric functions to calculate angular distances of celestial bodies, he attempted to estimate their distances. This approach significantly contributed to the development of measurement and calculation methods in astronomy.
Furthermore, Hipparchus’s work involved validating many observations and calculations found in Ptolemy’s “Almagest.” This emphasized the reliability and accuracy of his work and affirmed the validity of the observations presented in Ptolemy’s work.
Hipparchus’s studies greatly advanced measurement and calculation methods in astronomy and laid the groundwork for future generations. His observational approach to studying the sky, analyzing data using scientific methodology, and making deductions set the foundation for modern astronomy. Hipparchus’s contributions are considered a crucial element in the advancements and discoveries in astronomy and are seen as an important legacy that has paved the way for the field.
Figures like Aristotle, Galen, and Hipparchus were among the early pioneers of science and philosophy in the ancient world. Aristotle’s contributions to logic and natural philosophy, Galen’s contributions to medicine, and Hipparchus’s astronomical observations were pivotal steps that formed the basis of modern thought and science. The works of these great thinkers continue to be studied and serve as sources of inspiration even today. Their legacy provides a critical window into understanding the evolution of science.