The matter of limitation is to limit the state one is in and not want Gadlut (Greatness). Instead, one wants to remain in one’s present state forever, and this is called eternal Dvekut (Adhesion). Regardless of the measure of Gadlut that one has, even if one has the smallest Katnut (Smallness), if it shines forever it is considered having been imparted eternal Dvekut.
However, one who wants more Gadlut, it is considered luxury. And this is the meaning of, “any sorrow will be surplus,” meaning that sadness comes to a person because he wants luxuries. This is what it means that when Israel came to receive the Torah, Moses brought forth the people to the bottom of the mountain, as it is written, “and they stood at the nether part of the mount.”
(A mount (Hebrew: Har) means thoughts (Hebrew: Hirhurim)). Moses led them to the end of the thought and the understanding and the reason, the lowest degree there is. Only then, when they agreed to such a state, to walk in it without any wavering and motion, but to remain in that state as if they had the greatest Gadlut, and to be happy for it, this is the meaning of, “Serve the Lord with gladness.” This is so because during the Gadlut it is irrelevant to say that He gives them work to be in gladness, since during the Gadlut gladness comes by itself. Instead, the work of gladness is given to them for the time of Katnut, so that they will have joy although they feel Katnut. And this is a great work.
This is called the main part of the degree, which is a discernment of Katnut. This discernment must be permanent, and the Gadlut is only an addition. Also, one should yearn for the main part, not for the additions.