This piece was originally published in 2017. I decided to republish it after expanding its discussion.
There’s a shift in aspect from imperfective to perfective as Jesus describing his two house builders in Luke 6:47-49.
47 πᾶς ὁ ἐρχόμενος πρός με καὶ ἀκούων μου τῶν λόγων καὶ ποιῶν αὐτούς, ὑποδείξω ὑμῖν τίνι ἐστὶν ὅμοιος· 48 ὅμοιός ἐστιν ἀνθρώπῳ οἰκοδομοῦντι οἰκίαν ὃς ἔσκαψεν καὶ ἐβάθυνεν καὶ ἔθηκεν θεμέλιον ἐπὶ τὴν πέτραν· πλημμύρης δὲ γενομένης προσέρηξεν ὁ ποταμὸς τῇ οἰκίᾳ ἐκείνῃ, καὶ οὐκ ἴσχυσεν σαλεῦσαι αὐτὴν διὰ τὸ καλῶς οἰκοδομῆσθαι αὐτήν. 49 ὁ δὲ ἀκούσας καὶ μὴ ποιήσας ὅμοιός ἐστιν ἀνθρώπῳ οἰκοδομήσαντι οἰκίαν ἐπὶ τὴν γῆν χωρὶς θεμελίου, ᾗ προσέρηξεν ὁ ποταμός, καὶ εὐθὺς συνέπεσεν, καὶ ἐγένετο τὸ ῥῆγμα τῆς οἰκίας ἐκείνης μέγα.
Note that the imperfective οἰκοδομοῦντι is used immediately before a set of sequential tasks that make the duration of house building explicit in the text. The imperfective οἰκοδομοῦντι is used because at the time of that proposition, the event is unbounded. That is, ὃς ἔσκαψεν καὶ ἐβάθυνεν καὶ ἔθηκεν θεμέλιον ἐπὶ τὴν πέτραν denotes the internal temporal structure of οἰκοδομοῦντι. Using the imperfective here is, in a sense, akin to a narrator using an imperfective form of λέγω to introduce a long monologue. “a man building a house…first this…then that…” This is an important grammatical choice to take note of: different languages begin procedural lists in different ways.
In communicative language learning, discovering and then practicing how a given language (and culture!) forms a list of steps in a process or the structure of a larger procedure is an essential piece of learning the language. The use of the imperfective aspect is one way that Ancient Greek begins such lists, but it is not something you will likely find in grammars of the language.
Conversely the perfective οἰκοδομήσαντι is used for the builder who just built the house without any internal steps within its construction, at least not any internal steps that matter. The lack of the foundation itself is the salient point. The process of building is, then, effectively irrelevant. Luke presents Jesus using the perfective as a means gloss over the rest. This is a linguistic choice on the part of Luke’s Jesus to draw more attention to the no internal temporal structure here, just the simple event: οἰκοδομήσαντι.