In plain words
Why so? However great a king may be, he must fall under certain rules and laws laid down for the sake of proper government, and abide by them. Even though these laws were enacted by himself, once he has enacted them he too becomes bound by them — he must be. Even should he defy them or overstep them and act so, the principle 'as the king, so the people' will come into force. Therefore the lawmaker must conduct himself in accordance with the rules of law he has made. There is no other way for him to go. It is the ruler's duty to look after the welfare of his people; their welfare alone is the ruler's own welfare, and so it is his prescribed duty to fulfil their legitimate desires. For that reason, within the machinery of the state, he does not manage every matter personally by himself, but institutes various departments so that his system of governance may run smoothly.
If the ruler of this earthly world alone lays down so many regulations and establishes them so as to govern and safeguard the welfare of the country, then think how many precise rules and duties God — the ruler of the universe, the lord of the worlds, the lord of the cosmos, the very refuge of all the worlds — must have had to ordain for running the machinery of creation. Consider it. The order of creation is furnished with many branches and sub-branches; each branch is kept separately divided. Every branch has its own heads, and for them a fitting staff, with arrangements made in a suitable way. Here, devotees' prayers must be delivered to whichever branch they belong to, and to that branch alone. So if, whether through ignorance or by mistake, a prayer is sent to the wrong department, what does that department's head do? He simply pushes it aside, saying that the letter does not belong to his branch and that he has nothing to do with it, without involving himself in it at all. Hence our prayers are properly addressed only to whichever branch they truly belong to.
Over rain, Varuṇa is the presiding deity. A prayer concerning rain must go to Varuṇa's