1,354. Starting Hilchos Taaniyos

Hilchos Kiddush HaChodesh 19:16

We have completed our analysis of all the calculations necessary to determine the moon’s visibility, as well as the examination of the witnesses. Everything should now be understandable to insightful people so there’s no reason for them to be in the dark regarding any field of Torah. Because the Rambam has addressed this material at length here, there’s no need to go looking for this information elsewhere. As Isaiah 34:16 says, “Seek the book of God and read it; nothing will be lacking.”

Hilchos Taaniyos 1:1

There is a positive mitzvah in the Torah to cry out and sound trumpets in times of communal troubles, as per Numbers 10:9, “when enemies attack you, sound the trumpets....” The intent is that whenever we are besieged by troubles like famine, plague, locusts, etc., we should cry out to God and sound the trumpets because of them.