The picture is clearly divided into left and right, as there are no people in the middle. The right and left are marked by the central figures, Platon and Aristoteles. Platon is seen on the left, pointing his finger to the skies, possibly referring to one of his most known ideas: “The World of Ideas”. To the right, just like Platon, you can see Aristoteles carrying one his works as a thick tome, as you can read on the painting, it is his Ethics to Nicomacon.
To the left with a bright golden armor, it is likely Alexandre the Great, student of Platon and, after his death, of Aristoteles, Platon’s own disciple who continues his master task to educate one of the greatest generals to ever live.
On the right, close to the center, lying on the stairs, you see Diogenes, proeminente cynic and self-entitled disciple of Antisthenes.
To the extreme left, to the right of a baby and wearing a green hood, you can see Zenon of Citium, founder of Stoicism, doctrine that inspires itself on Socrates and that ended up finding its way to Roman Emperor Marcus Aurelius.
There are several more historic figures depicted in this anachronistic painting, some of them lived more than a thousand years apart, and, in fact, you can even a find Raffaello himself hiding in this painting that he himself drew.