Aelian, Historia Varia 3.1:
When Anaxagoras of Clazomenae was talking seriously with his companions, someone came to him and told him that his two sons, the only ones he had, were dead. Anaxagoras, not a bit disturbed, said, that he knew that he had fathered mortals.
When Xenophon was sacrificing, a herald from Mantineia came to him saying that his son Gryllus had died. Xenophon set aside his garland and finished sacrificing. When the messenger then added to the previous sentence the fact that he had at least died victorious, Xenophon put the garland back on his head. This story is common, and has made its rounds among the masses.
Dion, the son of Hipparinus and the associate of Plato, happened to be engaged in some common business of the people, when his son fell from the roof down to the courtyard and died. Dion did not turn his attention toward this, but continued doing what he had been working on at first, and finished the business he was engaged in.
They say that Antigonus the Second, when some people brought his son’s corpse to him from the battlefield, looked upon it and without changing color or shedding a tear, praised him as a good soldier and ordered that his body be buried.
Edward Gibbon, The Decline and Fall of the Roman Empire (Chp. V):
The emperor Gallienus, who had long supported with impatience the censorial severity of his father and colleague, received the intelligence of his misfortunes with secret pleasure and avowed indifference. “I knew that my father was a mortal,” said he; “and since he has acted as it becomes a brave man, I am satisfied.” Whilst Rome lamented the fate of her sovereign, the savage coldness of his son was extolled by the servile courtiers as the perfect firmness of a hero and a stoic.
᾿Αναξαγόρᾳ τις τῷ Κλαζομενίῳ σπουδάζοντι πρὸς τοὺς ἑταίρους προσελθὼν ἔφη τεθνηκέναι οἱ τοὺς δύο παῖδας οὕσπερ οὖν εἶχε μόνους ὁ ᾿Αναξαγόρας. ὃ δὲ μηδὲν διαταραχθεὶς εἶπεν ‘ᾔδειν θνητοὺς γεγεννηκώς.’
Ξενοφῶντι θύοντι ἧκέ τις ἐκ Μαντινείας ἄγγελος, λέγων τὸν υἱὸν αὐτοῦ τὸν Γρύλλον τεθνάναι· κἀκεῖνος ἀπέθετο μὲν τὸν στέφανον, διετέλει δὲ θύων. ἐπεὶ δὲ ὁ ἄγγελος προσέθηκε τῷ πρότερον λόγῳ καὶ ἐκεῖνον τὸν λέγοντα ὅτι νικῶν μέντοι τέθνηκε, πάλιν ὁ Ξενοφῶν ἐπέθετο τῇ κεφαλῇ τὸν στέφανον. ταῦτα μὲν οὖν δημώδη καὶ ἐς πολλοὺς ἐκπεφοίτηκεν.
Δίων δὲ ὁ ῾Ιππαρίνου μὲν παῖς Πλάτωνος δὲ ὁμιλητὴς ἔτυχε μὲν χρηματίζων ὑπέρ τινων δημοσίων καὶ κοινῶν πραγμάτων, ὁ δὲ παῖς αὐτοῦ ἐκ τοῦ τέγους κατενεχθεὶς ἐς τὴν αὐλὴν τὸν βίον κατέστρεψεν. οὐδὲν οὖν ἐπὶ τούτοις μετεβάλετο ὁ Δίων, ἀλλ’ ὅπερ οὖν ἐξ ἀρχῆς ἔπραττε, τοῦτο καὶ δρῶν διετέλεσεν.
᾿Αντίγονόν γε μήν φασι τὸν δεύτερον ἐπεί τινες τὸν υἱὸν αὐτῷ ἐκ τῆς παρατάξεως ἐκόμισαν νεκρόν, εἶδε μὲν αὐτόν, οὐδὲν δὲ τρέψας τοῦ χρωτός, οὐδὲ μὴν ἐπιδακρύσας, ἐπαινέσας δὲ ὡς ἀγαθὸν στρατιώτην, θάπτειν προσέταξεν.