Halakhah zu Jechezkiel 34:78

Because Scripture mentioned “God called the light ‘yom’ (day)”, it needed to tell us how one should count a day of the Torah. For the word “yom” has two meanings (a period of daylight, 12 hours, and a 24-hour period). Therefore it says that these two beginnings, namely dusk and dawn, encompass the Torah’s day. For ‘erev (dusk) refers to the time when shapes merge and are not distinguishable to the eye, as in the verse “They intermingled (vayit’arvu) among the nations” (Psalms 106:35). Boker (dawn) is the time when the forms are distinguishable and are recognizable and examinable, as in the verses “the priest need not examine (yevaqqer)” (Leviticus 13:36), “As a shepherd (vaqqarat) tends his flock” (Ezekiel 34:12). The term yom (day) encompasses both these times, for a single motion includes both. Similarly we find “He created male and female…and called their name ‘Adam’” (Genesis 5:2), while it is also written “And [the Lord, God,] made for Adam and his wife garments of hide and He dressed them” (ibid. 3:21).²² We see that the name “Adam” has a double meaning, sometimes referring to the entire human species, both male and female, and sometimes only to the male (or a specific male). Again it is clear from the description of Creation that a day is from evening to evening.