What is at first obvious and clear to us is rather jumbled together. And later elements and principles come to be knowable from these things when we distinguish them. Therefore it is necessary to proceed from universals to particulars: for the whole is more knowable in sense perception, and the universal is a certain whole, while the universal embraces many things as parts. And the same thing occurs in this way also with names in relation to an account (logos). For a whole signifies a something, i.e. indiscriminately, a circle, for example, but the definition of a circle divides it into particulars. And small children (ta paidia) at first call all men fathers and all women mothers, and later they distinguish each one of these (Translation mine, Aristotle, Physics 184a21-184b14).
It is “obvious,” to steal an overused term the all-seeing Aristotle often employs, to many readers that Aristotle’s “universal” and “particular” here must be different than his usage elsewhere. What exactly is he getting at? Since he gives two examples at the end of this section, we can probably gain the best interpretation by looking at them. The first seems rather straightforward, it takes much less conceptually to understand the term “circle,” though it certainly conjures up something in even the most basic minds. Yet, the definition of a circle will involve many constituent parts, as one of Euclid’s definitions demonstrates: “A circle is (1) a plane figure (2) contained by one line (3) such that all the straight lines (4) falling upon it from one point among those lying within the figure (5) equal one another.” Alternatively, perhaps, maybe Aristotle’s point is there are many terms in the one: shape, round, etc.
More puzzling is his remark on children calling all men and women fathers and mothers. In what sense do children “call” men and women fathers and mothers?
Here are some options on what he could mean:
A) Each child thinks that every man and woman is also a father and mother, because in his own case, obviously, his father is a man and a man is his father, and his mother is a woman and a woman is his mother.
B) Each child (a baby?) thinks that any adult it sees is a parent, in the loose, naive way such a mind would think this, possibly because the adult is a potential instrument of wish-granting.
I am also interested in the examples of the circle and the child-calling: are they supposed to be entirely analogous or are different points being made? There is a difference but it is difficult to express exactly what the relevant distinction each example has for Aristotle’s purposes. It seems that the circle example is showing how a broad term or concept can also be understood as consisting of parts (though interpretation seems susceptible of taking this is many ways). But the child-calling example, on first take, is about a child who displays only the first step of the circle example, and badly botching it at that, since it perceives men and fathers as “jumbled together.”
 ἔστι δ’ ἡμῖν τὸ πρῶτον δῆλα καὶ σαφῆ τὰ
συγκεχυμένα μᾶλλον· ὕστερον δ’ ἐκ τούτων γίγνεται γνώριμα
τὰ στοιχεῖα καὶ αἱ ἀρχαὶ διαιροῦσι ταῦτα. διὸ ἐκ τῶν κα-
θόλου ἐπὶ τὰ καθ’ ἕκαστα δεῖ προϊέναι· τὸ γὰρ ὅλον κατὰ
τὴν αἴσθησιν γνωριμώτερον, τὸ δὲ καθόλου ὅλον τί ἐστι· (25)
πολλὰ γὰρ περιλαμβάνει ὡς μέρη τὸ καθόλου. πέπονθε δὲ
(184b) ταὐτὸ τοῦτο τρόπον τινὰ καὶ τὰ ὀνόματα πρὸς τὸν λόγον· (10)
ὅλον γάρ τι καὶ ἀδιορίστως σημαίνει, οἷον ὁ κύκλος, ὁ δὲ
ὁρισμὸς αὐτοῦ διαιρεῖ εἰς τὰ καθ’ ἕκαστα. καὶ τὰ παιδία τὸ μὲν πρῶτον προσαγορεύει πάντας τοὺς ἄνδρας πατέρας καὶ
μητέρας τὰς γυναῖκας, ὕστερον δὲ διορίζει τούτων ἑκάτερον.