Shavuot: Kedushat Levi: Youthfulness
The Sages taught that God appeared to Israel at Sinai as an old man, while at the Exodus He appeared to them as a young lad (Pesikta Rabbati 21:5). This alludes to the two forms of the service of the Creator.
In the first, a person serves the Creator simply because “He is the Great Ruler.” He does not consider the goodness and lovingkindness that God bestows on him, because such favors and pleasures are as nothing compared to the great delight of the very act of the service of the Creator. Such a person knows that he worships the great and powerful King, whose servants number in the millions, and whose “glorious chariots” are infinite in number. This is called greatness of mind, wherein one serves the Creator with the greatness of his intellect.
There is another kind of worship in which one serves the Creator because the Creator grandson much kindness and goodness. This person worships the Creator with smallness of mind.
At the Exodus, Israel beheld God’s miracle and wonders: the punishment of the Egyptians by the Ten Plagues, the splitting of the Sea, and the spoils of Egypt. They then worshiped God with smallness of mind. This is what the Rabbis meant when they said, “At the Sea, God appeared to Israel as a youth,” for a youth has a limited mind; and they served Him then out of smallness of mind.
During the giving of the Torah at Sinai, “the pollution of Israel departed (Shabbat 146a),” so that no earthly pleasures held any importance for them compared with the service of the Creator. All of their service of the Creator was performed solely, “because He is the Great Ruler.” This is greatness of mind. This is what the Rabbis meant when they said, “at Sinai, God appeared to Israel as an old man,” as one who possesses a great mind.
Whoever serves God with greatness of mind suffers no fear or trepidation from any external events. Even though it may appear that he is beset by tribulations, inwardly he does not consider it tribulation, for he is firmly confident that no harm will befall him.
But he who worships God with smallness of mind is gripped even inwardly with great fear from everyday troublesome events. Because of this, the forces of impurity encompass him and he falls under their control. (Kedushat Levi; Yitro)