We know that days of the year are established by days and nights cycling. The question arises is the fact that there are days and nights the cause for days in the calendar or are they just a sign to determine it? Another question is: Are the days and nights caused by having the sun and moon out or are the sun and moon a sign of day and night?

We find on day one of creation that the light and darkness served together in a mixed fashion. This was before Hashem created on Wednesday the sun and moon and stars. From this fact we see that the sun coming up or going down does not cause day or night it is just a sign.

Another proof that it is only a siman not a sibah is from the mabul where there was no day and night. We see that after Noach brought his korbanos Hashem promised that “Yom Valayla – Lo Yishbosu.” Which means that during the mabul none of stars and moon or sun moved. We see from here too that the fact the Torah says the mabul lasted twelve months that the days of the year were not dependent on the sun or the moon.

Regarding the second question whether day is established by the sun and night by the moon or is it just a siman? There would be a nafka mina if a miracle happened and the sun would come up after it went down would it still be day or is it really night with the sun shining?

Again, here too the fact that there was ohr and choshech on first day even though the sun and moon were not created till the fourth day is a clear indicator that it is just a siman of yom to have sun and a siman of Layla to have the moon.

We could bring a raya that light is a cause for it to be called yom. We find when the Yidden circumcised themselves the night before yetzias Mitzrayim. Rashi explains that on that night they were given two mitzvos the blood of Pesach and blood of milah. The question is, how could they do a bris at night it is supposed to be done during the day? The answer is that since we find that the night of yetzias Mitzrayim was light a whole night therefore it was considered daytime. We see that light is considered day.

From the story of the fact that Yehoshua held the sun and the moon in place for thirty-six hours and thereby waited and Shabbos was pushed off. We see that in the event one is in the North Pole he should not count the day as every twenty four hours but rather every six months would be a day. This is the opinion of the Redal on Pirkei Dreb Eliezer. We don’t pasken this way.

With this we can understand the story of Nakdimon that the sun came out again and therefore he won the bet with the Hegmon as the sun coming out again was a sign that it was still day. The Maharsha disagrees. But the Gevuros Ari says this chiddush that if the son comes back out again that it is still day!

May we be zocheh to see the ohr Haganuz of Moshiach Tzidkeinu Amen