Philostratus (? the Athenian), aka Flavius Philostratus major (fl. after A.D. 217), Εἰκόνες = Imagines 2.33: Philostratus describes among a series of pictures an image of the madness of Heracles.


Fight on, noble men, toward this Heracles and approve of him. May he be held back from this remaining child, for two already lie here and his hand is shooting still, as is becoming of Heracles. Your challenge is great. It is no less than those labors he approached before his madness. But, fear nothing: he is far from you staring at Argos under the impression that he is murdering the offspring of Eurystheus. I, though, have heard him in Euripides’ play, leading his chariots and goading his horses and leaving to destroy Eurystheus’ home. For the thing he could not escape was the madness. A terrible thing to draw the mind from reality into the unreal. For those who stand by this was sufficient. Yet, for you the moment of the painting is come. The bedroom to which he was assailing holds Megara and his son still; but it also has baskets and lustrations and barley corns and fire-wood and a crater, all the property of Herkeios; all this has been kicked over and the bull is standing amidst; but he dragged all the victims toward the altar, the offspring born to him and also his lion's skin (lies there at the altar). One child has been shot in the neck and the arrow has rifled through the throat, tender as it was. The second child lies stretched out, shot through to the chest and the barbs of the arrow burst out through the middle of his spine, as if it were bursting clear openings into his abdominal cavity. Their cheeks are drenched in tears. Nor would you be astonished if they wept over something — About the weeping for the children, in fact, their weeping was golden and slight, but equally great. As Heracles was shooting his arrows, all the inhabitants living around came, like herdsmen around a raving bull, to ask who was plotting against them and to restrain whoever was causing the row or somebody that might be disturbing their peace. One of them tried to stop his hands, another tripped him up, and others still diverted him. He, meanwhile, had no awareness of them at all. Rather, he smashed through them as they came at him and dashed them down. He was foaming abundantly from his mouth, smiling grimly and strangely and staring with his eyes at what he was doing, but driving his gaze’s focus at what was deceiving him. His throat was full and the neck was filled with rage; his veins were bulging all over him. Through these surged into his brain all that fueled the illness. The Erinys, though, who has been governing all this you have often seen in the theatre; but here you wouldn’t see her. For she was manipulating Heracles and dancing within his chest, buffeting and muddying his rationality. This is what the painting illustrates; the poets binge on the passage and restrict Heracles and all these details, but then report that Prometheus was later freed by this man [who is raging here].

The following text is attributed to C.L. Kayser's 1871 Teubner edition and lifted (with minor corrections) from Perseus.Tufts.Edu.
ΗΡΑΚΛΗΣ ΜΑΙΝΟΜΕΝΟΣ.
κγ. μάχεσθε, ὦ γενναῖοι, ῾πρὸς᾽ τὸν Ἡρακλέα καὶ πρόβατε. ἀλλὰ τοῦ λοιποῦ γε παιδὸς ἀπόσχοιτο δυοῖν ἤδη κειμένοιν καὶ στοχαζομένης τῆς χειρός, ὡς καλὸν Ἡρακλεῖ. μέγας μὲν ὑμῖν ὁ ἆθλος καὶ μείων οὐδὲν ὧν πρὸ τῆς μανίας αὐτὸς ἤθλησεν. [p. 377] ἀλλὰ δείσητε μηδέν: ἄπεστιν ὑμῶν Ἄργος βλέπων καὶ τοὺς Εὐρυσθείδας ἀποκτεῖναι δοκῶν, ἐγὼ δὲ ἤκουσα αὐτοῦ παρ᾽ Εὐριπίδῃ καὶ ἅρματα ἡγουμένου καὶ κέντρα ἐς τοὺς ἵππους φέροντος καὶ τὴν Εὐρυσθέως οἰκίαν ἀπειλοῦντος ἐκπέρσειν, ἀπατηλὸν γάρ τι ἡ μανία καὶ δεινὸν ἐκ τῶν παρόντων ἀγαγεῖν ἐς τὰ μὴ παρόντα. τούτοις μὲν οὖν ἀπόχρη ταῦτα, σοὶ δὲ ὥρα γίγνεσθαι τῆς γραφῆς: ὁ μὲν θάλαμος, ἐφ᾽ ὃν ὥρμηκε, Μεγάραν ἔχει καὶ τὸν παῖδα ἔτι, κανᾶ δὲ καὶ χέρνιβα καὶ οὐλαὶ καὶ σχίζαι καὶ κρατήρ, τὰ τοῦ Ἑρκείου, λελάκτισται πάντα καὶ ὁ μὲν ταῦρος ἕστηκεν, ἱερεῖα δὲ προσέρριπται τῷ βωμῷ βρέφη τὰ γένη [ἅμα] καὶ τῇ λεοντῇ. προσβέβληται δ᾽ ὁ μὲν κατὰ τοῦ λαιμοῦ καὶ δι᾽ ἁπαλῆς γε τῆς φάρυγγος ἐκδεδράμηκεν ὀιστός, ὁ δὲ ἐς αὐτὸ διατέταται τὸ στέρνον καὶ ὄγκοι τοῦ βέλους μέσων διεκπεπαίκασι τῶν σπονδύλων, ὡς δῆλα ἐς πλευρὰν ἐρριμμένου. αἱ παρειαὶ δὲ αὐτῶν διάβροχοι καὶ μὴ θαυμάσῃς, εἰ ἐδάκρυσάν τι, περὶ τοῦ δακρῦσαι παισὶ γὰρ χρυσοῦν τὸ δάκρυον καὶ μικρὸν δ᾽ ἴσως καὶ μέγα. οἰστροῦντι δὲ τῷ Ἡρακλεῖ περίκειται πᾶς ὁ τῶν οἰκετῶν δῆμος, οἷον βουκόλοι ταύρῳ ὑβρίζοντι, δῆσαί τις ἐπιβουλεύων καὶ κατασχεῖν τις ἀγῶνα ποιούμενος καὶ κεκραγὼς ἕτερος, ὁ δ᾽ ἤρτηται τῶν χειρῶν, ὁ δ᾽ ὑποσκελίζει, οἱ δὲ ἐνάλλονται: τῷ δὲ αἴσθησις μὲν αὐτῶν οὐδεμία, ἀναρριπτεῖ δὲ τοὺς προσιόντας καὶ συμπατεῖ, πολὺ μὲν τοῦ ἀφροῦ διεκπτύων, μειδιῶν δὲ βλοσυρὸν καὶ ξένον καὶ τοῖς ὀφθαλμοῖς ἀτενίζων ἐς αὐτά, ἃ δρᾷ, τὴν δὲ τοῦ βλέμματος ἔννοιαν ἀπάγων ἐς ἃ ἐξηπάτηται. βρυχᾶται δὲ ἡ φάρυγξ καὶ ὁ αὐχὴν ἐμπίπλαται καὶ ἀνοιδοῦσιν αἱ περὶ αὐτὸν φλέβες, δι᾽ ὧν ἐς τὰ καίρια τῆς κεφαλῆς [p. 378] ἀναρρεῖ πᾶσα χορηγία τῆς νόσου. τὴν Ἐρινὺν δέ, ἥ ταῦτα ἴσχυσεν, ἐπὶ μὲν τῆς σκηνῆς εἶδες πολλάκις, ἐνταῦθα δὲ οὐκ ἂν ἴδοις, ἐς αὐτὸν γὰρ ἐσῳκίσατο τὸν Ἡρακλέα, καὶ διὰ τοῦ στέρνου χορεύει μέσου αὐτῷ ἔσω σκιρτῶσα καὶ τὸν λογισμὸν θολοῦσα. μέχρι τούτων ἡ γραφή, ποιηταὶ δὲ προσπαροινοῦσι καὶ ξυνδοῦσι τὸν Ἡρακλέα καὶ ταῦτα τὸν Προμηθέα φάσκοντες ὑπ᾽ αὐτοῦ λελύσθαι. Flavii Philostrati Opera, Vol 2. Philostratus the Lemnian (Philostratus Major). Carl Ludwig Kayser. in aedibus B. G. Teubneri. Lipsiae. 1871.