It must come from a kosher animal (Mishnah Rosh HaShanah 3:2), but not from a cow because of its association with the sin of the golden calf (the Talmud says, “A prosecutor cannot be a defender at the same time”).
According to Rabbi Abbahu, the ram’s horn is best because its curved shape symbolises humble submission and it reminds us of the story of the binding of Isaac, with its message of faith in God.
The shofar is not a contrived musical instrument. Its aim is not to put us to sleep with its beauty but to wake us up with its eeriness.
Rav Kook pointed out that the shofar needs very little preparation, unlike the silver trumpets that were used in the Temple. The shofar represents the direct call of the Divine.
Similarly, the exterior of the shofar should be unadorned with coloured designs, though it can be decorated with geometrical patterns and with Biblical verses or the name of the community.
The shofar has three basic sounds: t’kiah, a long unbroken sound; sh’varim, three shorter sounds like wailing, and t’ruah, nine staccato notes like sobbing, and then comes a concluding t’kiah.
Samson Raphael Hirsch says, “T’kiah calls you from your continuous living in the outer world and brings you through your innermost self to God. Sh’varim bids you immerse your complete self in this rock-shattering God-concept. T’ruah makes you quiver. T’kiah puts strength into you and lifts you to a life before God”.
In Biblical times the shofar was often used as a call to arms. Philo of Alexandria observed that the shofar was not only a call to advance but also a call to retire from battle. Hence it is a call of thanks to God, who halts the wars between the nations and the struggle between the elements of nature, bringing peace and harmony to the universe.