Acts 1:7

χρόνους ἢ καιρούς : Blass regards the two as synonymous, and no doubt it is difficult always to maintain a distinction. But here χρόνους may well be taken to mean space of time as such, the duration of the Church's history, and καιρούς the critical periods in that history. ὁ μὲν καιρὸς δηλοῖ ποιότητα χρόνου, χρόνος δὲ ποσότητα (Ammonius). A good instance of the distinction may be found in LXX Nehemiah 10:34 : εἰς καιροὺς ἀπὸ χρόνων, “at times appointed”; cf. 1 Thessalonians 5:1. So here Weiss renders: “zu kennen Zeiten und geeignete Zeitpunkte”. In modern Greek, whilst καιρός means weather, χρόνος means year, so that “in both words the kernel of meaning has remained unaltered; this in the case of καιρούς is changeableness, of χρόνων duration” (Curtius, Etym., p. 110 sq.); cf. also Trench, N. T. Synonyms, ii., p. 27 ff.; Kennedy, Sources of N. T. Greek, p. 153; and Grimm-Thayer, sub v. καιρός. ἐξουσία, authority, R.V. either as delegated or unrestrained, the liberty of doing as one pleases (ἔξεστι); δύναμις, power, natural ability, inherent power, residing in a thing by virtue of its nature, or, which a person or thing exerts or puts forth so δύναμις is ascribed to Christ, now in one sense, now in another, so also to the Holy Spirit as in Acts 1:8; cf. Acts 10:38; Luke 4:14; Romans 15:13; Bengel, Luke 4:36, and Grimm-Thayer, Synonyms. Sub v. δύναμις.