(א) וַיֹּ֤אמֶר יְהוָה֙ אֶל־מֹשֶׁ֣ה וְאֶֽל־אַהֲרֹ֔ן בְּאֶ֥רֶץ מִצְרַ֖יִם לֵאמֹֽר׃ (ב) הַחֹ֧דֶשׁ הַזֶּ֛ה לָכֶ֖ם רֹ֣אשׁ חֳדָשִׁ֑ים רִאשׁ֥וֹן הוּא֙ לָכֶ֔ם לְחָדְשֵׁ֖י הַשָּׁנָֽה׃
(1) And the LORD spoke unto Moses and Aaron in the land of Egypt, saying: (2) ’This month shall be unto you the beginning of months; it shall be the first month of the year to you.
החדש הזה. הֶרְאָהוּ לְבָנָה בְּחִדּוּשָׁהּ וְאָמַר לוֹ כְּשֶׁהַיָּרֵחַ מִתְחַדֵּשׁ יִהְיֶה לְךָ רֹאשׁ חֹדֶשׁ (מכילתא). וְאֵין מִקְרָא יוֹצֵא מִידֵי פְשׁוּטוֹ, עַל חֹדֶשׁ נִיסָן אָמַר לוֹ, זֶה יִהְיֶה רֹאשׁ לְסֵדֶר מִנְיַן הֶחֳדָשִׁים, שֶׁיְּהֵא אִיָּר קָרוּי שֵׁנִי, סִיוָן שְׁלִישִׁי:
החדש הזה — He showed him the moon in the first stage of its renewal, and He said to him, “The time when the moon renews itself thus, shall be unto you the beginning of the month”. (The translation therefore is: “This stage of renewal (חדש) shall be the moment of beginning the months”; cf. Mekhilta; Shemot Rabbah 15). But no Scriptural verse can lose its literal meaning, and He really spoke this in reference to the month Nisan: this month shall be the beginning in the order of counting the months, so that Iyar shall be called the second, Sivan the third.
S'fat Emet, Exodus12:2
Why does Israel count by the moon, with each month starting when the new moon emerges? Because the moon, unlike the sun, waxes and wanes, nearly disappears and then grows bright again. So the Jewish people go through cycles of prosperity and suffering, knowing that even in darkness there are brighter days ahead.
Why does Israel count by the moon, with each month starting when the new moon emerges? Because the moon, unlike the sun, waxes and wanes, nearly disappears and then grows bright again. So the Jewish people go through cycles of prosperity and suffering, knowing that even in darkness there are brighter days ahead.

