– – ⏑ – – – ⏑ – ⏑ – ⏑ ⏑ σφαζ αιμ|ατου | θ_εα_ς βωμ|ον η | μετεισ|ι σε (_Andromache_, 260). (Synizesis is specially common in the various cases of θεός and θεά.) Finally, two important rules of rhythm remain to be stated. First, there must be a “cæsura”[862] in either the third or the fourth foot. A cæsura is a gap between words in the middle of a foot. Either the third foot, then, or the fourth must consist partly of one word, partly of another. It is indicated in scansion by the sign ‖. Many verses have this necessary cæsura in the third foot only, _e.g._:— ⏑ – ⏑ – – – ⏑ – – – ⏑ ⏑ απανθ | ο μακρ|ος ‖ καν|αριθμ|ητος | χρονος (_Ajax_, 646). Many show it in the fourth only:— – – ⏑ – ⏑ – ⏑ – – – ⏑ ⏑ προς τησδ|ε της | γυναικ|ος ‖ οικτ|ειρω | δε νιν (_Ibid._, 652). A still larger number have cæsura in both places:— – – ⏑ – – – ⏑ – – – ⏑ ⏑ φρουρας | ετει|ας ‖ μηκ|ος ‖ ην | κοιμωμ|ενος (_Agamemnon_, 2). This usage is essential to rhythm. It is of course possible for every foot in the line to exhibit a cæsura, but one in the midst is necessary to prevent the line from falling into pieces. That coextension of word and foot which is naturally frequent must at one point be emphatically excluded, so that the whole line may be felt as a single rhythmical whole. Such “lines” as – – ⏑ – ⏑ – ⏑ – – – ⏑ ⏑ ταυτην αναξ λεγει καλην ειναι πολιν, or ⏑ – ⏑– – – ⏑ – ⏑ – ⏑ ⏑ Οδυσσεως δουλοι μαχουμενοι ταχα, are utterly impossible.[863] The first falls into six scraps, and the second into two mere lumps, of equal length. If a breach of the rule ever occurs, it is for a special reason. When Sophocles (_Œd. Tyr._, 738) writes ὦ Ζεῦ, τί μου δρᾶσαι βεβούλευσαι πέρι; the dragging rhythm well represents the dawning dread of Œdipus. But the main cæsura may be dispensed with if the third foot ends with an elision, apparently because, if the word could be written in full, the fourth foot would be divided between two words. Thus:— χαῖρ’· οὐ γὰρ ἐχθαίρω σ’· ἀπώλεσας δ’ ἐμέ (_Alcestis_, 179). ζητοῦσι τὸν τεκόντ’· ἐγὼ δὲ διαφέρω (_Heracles_, 76). The other rule is that generally called “the rule of the Final Cretic”.[864] It is most simply stated thus: if there is a cæsura in the fifth foot, that foot must be an iambus, _e.g._:— ⏑ – ⏑ – μη με̄ στυγησῃς· ουχ εκων | γαρ ‖ αγγ|ελω (_Troades_, 710). ⏑ – ⏑ – τον τουδε νεκρον ουκ αθαπτ|ον ‖ αν | λιποις (_Ibid._, 738). This rule does not exclude from the first half of the foot long _monosyllables_ which are in meaning and syntax closely connected with the “cretic” word or words. Thus τῶν σωμάτων is a quite correct ending, but not τούτων σωμάτων.