The “civilized” Greeks were not afraid of showing their pain because their identity was rooted firmly within. The “barbarian” Trojans’ identity was dependant upon the esteem and impressions of others (i.e., their identity was not internal to the same degree, but externally dependant) hence the ferociousness going into battle and the stoicism in burying their dead. Of course the Greeks conquered Troy. Lessing is studying the Laocoön group with a view to exploring the limits of art in expressing pain.
“A cry is the natural expression of physical pain. Homer’s wounded warriors not infrequently fall to the ground with a cry. Venus shrieks aloud at a mere scratch [Iliad V. 343], not because she must be made to represent the tender goddess of sensuality, but because suffering nature must have her due. Even iron Mars screams so horribly on feeling the lance of Diomedes that it sounds like the shouting of ten thousand raging warriors and fills both armies with terror [Iliad V. 859].
High as Homer raises his heroes above human nature in other respects, he still has them remain faithful to it in their sensitiveness to pain and injury and in the expression of this feeling by cries, tears, or invectives. In their deeds they are beings of a higher order, in their feelings true men.
I know that we more refined Europeans of a wiser, later age know better how to govern our mouths and our eyes. Courtesy and propriety force us to restrain our cries and tears. The aggressive bravery of the rough, early ages has become in our time a passive courage of endurance. Yet even our ancestors were greater in the latter than the former. But our ancestors were barbarians. To master all pain, to face death’s stroke with unflinching eye, to die laughing under the adder’s bite, to weep neither at the loss of one’s dearest friend nor at one’s own sins: these are the traits of old Nordic heroism. Palnatoko decreed that his Jomsburghers were not to fear anything nor even so much as mention the word “fear.”
Not so the Greek! He felt and feared, and he expressed his pain and grief. He was not ashamed of any human weakness, but it must not prevent him from attaining honor nor from fulfilling his duty. The Greek acted from principles whereas the barbarian acted out of his natural ferocity and callousness. In the Greek, heroism was like the spark hidden in the flint, which sleeps quietly as long as no external force awakens it, and robs it of its clarity or its coldness. In the barbarian, heroism was a bright, consuming, and ever-raging flame which devoured, or at least blackened, every other fine quality in him. When Homer makes the Trojans march to battle with wild cries, while the Greeks go in resolute silence, the commentators rightly observe that the poet thereby intends to depict the former as barbarians and the latter as civilized peoples. I am surprised that they did not notice a similar contrast of character in another passage [Iliad VII. 421]. Here the opposing armies have agreed to a truce and are busy burning their dead, which does not take place without the shedding of hot tears on both sides. But Priam forbids his Trojans to weep. He does this, Madame Dacier says, because he is afraid they may grow too softhearted and take up the battle on the following day with less courage. True! But why, may I ask, should only Priam fear this? Why does Agamemnon not issue the same command to the Greeks? The poet’s meaning goes deeper: he wants to tell us that only the civilized Greek can weep and yet be brave at the same time, while the uncivilized Trojan, to be brave, must first stifle all human feeling. “Weeping does not make me indignant” is the remark that Homer has the sensible son of wise Nestor make on another occasion” [Odyssey IV. 195] (Gotthold Ephraim Lessing, Laocoön, p 8-10).