Exodus 19:21-25

21 And the Lord said to Moses, “Go down and warn the people, lest they break through to the Lord to look and many of them perish. 22 Also let the priests who come near to the Lord consecrate themselves, lest the Lord break out against them.” 23 And Moses said to the Lord, “The people cannot come up to Mount Sinai, for you yourself warned us, saying, ‘Set limits around the mountain and consecrate it.’” 24 And the Lord said to him, “Go down, and come up bringing Aaron with you. But do not let the priests and the people break through to come up to the Lord, lest he break out against them.” 25 So Moses went down to the people and told them.

When there is an eclipse, we’re told not to look directly at the sun, as doing so could damage our eyes. The sun is a good thing and provides light and warmth and makes life possible, but it also has power to harm us if we don’t approach it properly. In the same way, the Lord’s presence is good for the people, but they will need to learn how to live in His presence. (This is, in fact, what the book of Leviticus will be about.)