βροτοῖσι τὸν πεσόντα λακτίσαι πλέον.
Aeschylus Agamemnon, 884-885
Mortals are generally inclined to
trample a man when he’s down.
Clytemnestra speaks these lines to her husband, explaining why she sent their son, Orestes, away to live with Strophius. Agamemnon has just returned from his time at Troy, the fabled hotbed of suffering and anguish for Greek heroes, and Clytemnestra wants to share with him why it’s been so bad for her during his absence.
She’s heard the rumors of the wounds he’s incurred and the deaths he’s experienced many times over.  It’s driven her to attempt suicide—not once but a few times; luckily household help (presumably) intervened. 
Strophius has been kind enough to point out that this Trojan War affair has opened up for her, Orestes, and Agamemnon’s kingdom potential for trouble:  Agamemnon’s absence no less than his death has left Argos at the mercy of mob lawlessness.  Without a ruler, Clytemnestra contends, the people at large (δῆμος) would do what’s in their nature and hatch a plot against the royal house in general and Orestes in particular.
Given the chance to see weakness, humans will exploit it their advantage. Plain and simple.
We’ll pass over the fact of Aeschylus’s drama that Clytemnestra has already devised a scheme for Agamemnon’s death, that she’s already got her plan in place. 
Clytemnestra speaks about the inclination of man to take advantage of another when he’s down as a way to let Agamemnon know she’s been thinking (deceptively, it turns out) about maintaining some sort of dynastic stability during his absence.
The entire speech is dense with meaning—par for the course with the Oresteia—and these two lines on the nastiness of mortals toward other men have a gnomic ring to them.
They pass dour judgement on human nature.
But should we expect any less from the first installment of a trilogy The Guardian (22 May 2015) described as a “nightmarish pattern of kill and counter-kill?”
 861-873: τὸ μὲν γυναῖκα…κατθανὼν μορφώματι.
 875-876: πολλὰς ἄνωθεν ἀρτάνας ἐμῆς δέρης / ἔλυσαν ἄλλοι πρὸς βίαν λελημμένης
 881: ἀμφίλεκτα πήματα
 883: δημόθρους ἀναρχία
 1377-1378: ἐμοὶ δ᾿ ἀγὼν ὅδ᾿ οὐκ ἀφρόντιστος †πάλαι / νίκης παλαιᾶς† ἦλθε. Following M.L. West’s edition (Teubner, 1991), I’ve obelized a good portion of these lines as corrupt (West: “corruptela non sanata”). The point is clear, however, that Clytemnestra’s been stewing over Agamemnon’s murder for some time. As a side comment, while we might see her rational for slaughtering Agamemnon as less than convincing, we’re not surprised to find that Clytemnestra has no moral doubt about the murder. At one point in the play (line 1406) she calls the right hand that struck Agamemnon down the “maker of justice” (δικαίας τέκτονος).