Someone asked me what Graeco-Arabic Medicine is in a previous post about bay leaf, if I didn't get it wrong. Anyway, that gives me a chance to write about the traditional philosophy, thank you for reminding me my friend.
The Graeco-Arabic traditions sprang from the wisdom of classical Greece since the 5th century and are still a cultural part in the Middle East and Indian subcontinent.
The four elements
The ancient Greece believed that the material universe was composed of four basic elements: Fire, Air, Water and Earth. There was another invisible element and most powerful element called Aether. Aether was the foundation of the four elements, and created them in the order of Fire, Air, Water and Earth, which was why Fire was the most energetic element of all.

Humans were also considered to be composed of the four elements, which got together and created a vital force called pneuma. Health of humans depended on pneuma to the ancient Greece.

The four qualities
The four qualities were Warmth, Dryness, Coldness and Moisture. Each of the four elements expresses two qualities, thus linking the elements. Fire is Dry and Warm, Air is Warm and Moist, Water is Moist and Cold and Earth is Cold and Dry.
The elements and qualities are also linked to seasons, daily time periods, climatic influences, medicines, etc. For example, Spring is considered to belong to the Air because it is Warm and Dry.

I kept this picture big so that you can read the texts clearly.
You are also welcome to view other links about Graeco-Arabic Medicine:
10 herbs from Graeco-Arabic Medicine series
Chapter 1: Milk Thistle for Treating Diabetes
Chapter 2: Olive Leaf to Treat Cardiovascular and Boost Immune System
Chapter 3: Feverfew to Prevent Migraine Headache
Chapter 4: Black Seed for Boosting Immune System
Chapter 5: Bay Leaf and Fruits for Treating Diabetes
Chapter 6: Carob Treats Diarrhea and High Cholesterol
Chapter 7: A Gift to Jesus Christ: Myrrh for Indigestion and Ulcers
Chapter 8: Senna: A Laxative and an Aid to Treat Constipation
Chapter 9: Chicory Helps Digest and Lower Blood Sugar
Chapter 10: Pomegranate Juice Lowers High Blood Pressure