Imam al-Sadiq (PBUH) said: Safeguard your writings and books because soon the occasion will arise that you will be in need of them.

Imam Ali (PBUH) said: Acquiring knowledge is not possible while the body (person) is tranquil.

The mule was highly valued in ancient Greece as well, for use as pack animals and to draw carriages. While boats were used when traveling long distances in ancient Greece, as the country was partially a group of islands, the average citizen rarely left their home area and depended upon the mule as the most common mode of transportation. Mules had much harder hooves than horses and were better suited to cover the rocky terrain found in Greece.

In the kingdom of Mari in northern Mesopotamia, the story was told that the King was reprimanded and asked to "Please …use a mule instead of the common horse", as his royal position demanded.

People of ancient Ethiopia gave the mule the highest status of all the animals.

Imam Zayn-al-Abideen (PBUH) said: Were people aware of what lies in the obtainment of knowledge, they would pursue it even though they had to make voyages and endanger their lives to obtain it.

The Holy Prophet (Peace be upon him and his progeny) said: The virtue of knowledge is more beloved with Allah than the virtue of worship.

To the north in Asia Minor, the Hittites were the most powerful of the early horse-people - - but they considered the mule to be at least three times more valuable in price than even a good chariot horse.

Sumerian texts from the third millennium BC stated the price of a mule was 20 to 30 shekels, seven times that of a donkey. At Ebla, the average price for a mule was 60 shekels.

Mules were, at that time, the preferred pack animal. Also in ancient Egypt, while the Pharaohs were carried about in fancy litters by servants, the common people often had the use of mule drawn carts. An Egyptian monument from Thebes depicts mules yoked to a chariot. Mule remains are frequent in the archaeological record, suggesting that mules had become a "mainstream" animal early on, used primarily for pulling wagons or transporting burden.

The inhabitants of Paphlagonia and Nicaea (the northern and northwestern parts of modern day Turkey) are said to have been the first to breed mules.

Mules were known in Egypt since before 3000 BC and for some 600 years - between 2100 BC and 1500 BC - - the Pharaohs sent expeditions into the Sinai to mine turquoise. The miners marked their route with carvings on rocks showing boats and mules (not camels!).