It’s a question that's captivated humanity for millennia, and the answers are as varied as the stars in the sky. Today, we're diving into a fascinating corner of this exploration, guided by the writings of Philo of Alexandria, a Jewish philosopher who lived in the first century CE. He offers a unique perspective on the nature of the soul, drawing on both Jewish scripture and Greek philosophical thought.

Philo grapples with the question of where exactly the soul resides, and what it's made of. He suggests that God, in His commands, hints that blood is the substance of the soul – but only a certain kind of soul. Specifically, the soul connected to our senses and our vitality. What about the rational, intellectual soul? That, according to Philo, is something else entirely.

He posits that we humans actually have a tripartite soul – three parts! There's the nutritive part, concerned with basic survival; the part connected to our senses; and then, the highest part, the one that dwells in reason. It’s this rational part that, according to Philo, echoing the sacred writer Moses, is "the substance of the divine spirit." Remember the creation story? "God breathed into his face the breath of life" (Genesis 2:7). That breath, Philo suggests, is what constitutes our rational life.

But what about the blood? Well, according to Philo, "The blood exists in every breath of flesh." (Deuteronomy 12:23). He emphasizes that blood is the "breath of all flesh" precisely because our flesh is where we experience senses and passions, but not intellect or higher thought.

And here's where it gets even more interesting. Philo distinguishes between the spirit and the blood, saying that "the spirit of blood" intimates that they are two distinct things. The essence of the soul, he argues, is truly spirit. However, this spirit isn't separate from the body. It's interwoven and mingled with the blood. It's all connected!

He uses the analogy of veins and "breathing channels" – perhaps he means arteries and veins – to illustrate this. These vessels carry both air and blood, each in different proportions, a carefully balanced mixture. Philo's description sounds remarkably like an ancient, philosophical take on the circulatory system!

But then, Philo takes a turn towards the metaphorical. He suggests that the "blood of the soul" can also be seen as that warm, fiery virtue we call courage. Someone filled with this courage, this wisdom, will despise fleeting pleasures, focusing instead on higher pursuits.

Conversely, someone who lives a profligate life, wandering aimlessly and indulging in laziness, is simply "fall[ing] upon his belly, as a reptile creeping upon the earth, and greedily licking up earthly things." Such a person, Philo argues, closes their life without ever tasting that "heavenly food" that souls desirous of wisdom receive.

So, what can we take away from Philo's musings? He paints a picture of humanity as complex beings, with different layers to our souls. He urges us to strive for the highest part, the rational part connected to the divine, rather than being consumed by earthly desires. It's a call to live a life of purpose, guided by reason and a thirst for wisdom. It's a reminder that we are more than just flesh and blood; we are also vessels of the divine breath.