Light as an eagle? Surely not

Avot 5:23 reads as follows: 

Yehudah ben Tema says: “Be as bold as a leopard, light as an eagle, swift as a deer and strong as a lion to do the will of your Father in Heaven”.

What's the relevance of the eagle? 

Seven species of eagle are found in Israel today and it is probable that not only the Tannaim but also anyone who kept the sheep, goats or poultry on which they feed would have been highly familiar with them.  However, the simile here is puzzling. “Be light as an eagle” has an almost poetical quality to it, but something is wrong. Eagles are amongst the very heaviest birds that fly; by avian standards they are anything but light. One may as well say “Be light as a hippopotamus”. What, then, is our Tanna trying to tell us?

Fortunately there is a plausible explanation, though not one that is obvious to modern thinkers because it requires getting into the mindset of Sages and philosophers in the era of the Tannaim, some two millennia back. 

Imagine a world that is composed of four elements: earth, air (or wind), fire and water.  Not just the planet Earth but everything in it is comprised of anything between one and four of these elements which, combined in different proportions, have different characteristics. Thus, for example, a tomato has a higher ratio of water to earth while a potato is quite the opposite. A chilli pepper has a higher ratio of fire to air, while a meringue has a higher ratio of air to fire, and so on.  Man is also composed of these four elements. All humans differ in their composition and that explains their character: some are fiery, others sanguine; some live on a lofty spiritual plain while others appear to have no aspirations that rise above the fulfilment of their basic bodily functions.

Taking these four elements further, it is accepted that all the problems faced by mankind are caused by an imbalance between them. Fire leads to anger and arrogance; air leads to vacuity and idle chatter; water leads to wealth, jealousy, pleasures of the flesh and to indulgence in the material world; earth, the heaviest element of all, leads to depression, indolence and hopelessness. The very largest and heaviest birds—for example the ostrich, the emu and the cassowary—do not fly. They are literally earthbound. Of birds that fly, the eagle with its heavy body has to make a far greater effort than do smaller birds to overcome the pull of its own “earthiness” in order to generate flight.

Returning to our metaphor, we are told to be “light as the eagle”. Just as the eagle has to make so great an effort to overcome its “earthiness”, so too should we make a great effort, when doing God’s will, of overcoming our own “earthiness” and the feelings of depression, indolence and hopelessness that accompany it.

Finally, while it is possible that this four-element theory, despite its apparently non-Jewish origin, would have been known to a Torah scholar, it is also possible that it actually originates from a Jewish source. An anonymous author on the Daat Emet website writes:

… Josephus (who lived in the first century CE and was commander of the Galilean forces during the Great Revolt — History of the wars of the Jews and the Romans, book 5, chapter 5:4) explains why the covering which divided the sanctuary from the Holy of Holies in the Temple was made of four threads of color: blue, purple, scarlet, and white. He claimed that the four colors represented the four elements in order to show a model of the world. Blue, the color of the skies, represents air, scarlet represents fire, purple is produced from a mollusk and represents the water from which it came, and white linen comes from the earth and represents it.