Why do we cover our eyes when saying the Shemah at certain times, but not at others?
Jews have a custom of covering our eyes while saying the Shemah (Deuteronomy Chapter 6, verses 4-9). We say the Shemah twice daily because it is written in the text itself (verse 7): “And you shall rehearse them with your children and speak of them, when sitting in your house and when walking on the way, when you lie down and when you rise.” The rabbis of the Talmud interpreted this verse to mean that we should recite the Shemah in the evening and in the morning. They called this part of the service “Kri’at Shemah,” the reading of the Shemah, and they believed we needed to focus deeply to truly grasp the meaning of calling the Eternal “One.” Also, the word Shemah means “hear” or “listen,” and when we cover our eyes it is easier to concentrate on the words we are saying.
There are other parts of the service during which we say the Shemah, but those are not moments that require the complete concentration of reciting the three paragraphs of the Shemah (Deuteronomy 6:4-9 and 11:13-21; Numbers 15:37-41). For example, during the Musaf service, we simply acknowledge that the Jewish people say the Shemah twice a day. And during the Torah service, as we are about to carry the Torah to be paraded through the people, we use the Shemah to affirm God’s unity, in a ritual of call and response that ensures that we, as a community, declare our conviction in the oneness of God. In both situations, and in others like that, we do not require the concentration needed to read, speak, teach, and mull over the words of the Shemah. Therefore, when we need to focus on this prayer, we cover our eyes, and when we need to affirm our convictions, we do it proudly, eyes open, with courage and commitment.