In plain words
department. Over that alone does he have authority. Just so, the sun is lord over radiance and over health; Gaṇapati is the head of the department of obstacles; over crops presides the Earth-goddess; over the harvest's medicinal herbs, the moon. Likewise every kind of power has its own fitting presiding lord. These have presiding deities, the adhiṣṭhāna-devatās, and they are called the adhiṣṭhāna lords. Each and every power of our senses has its own adhiṣṭhāna-devatā.
'But God is only one, is He not, and it is to Him alone that we have been praying — so why do our desires go unfulfilled?' To think and suppose so is a mistake, and that very mistake is our own weakness. God is indeed one alone — true, just as the Prime Minister, or the king, is but one. But the departments are different, each one distinct from the rest, and that is what we fail to grasp. If one writes a letter and posts it to another person's address, to whom does it actually reach? It reaches only the one whose address is on it, not the person actually intended. In just the same way, your prayer must be addressed to whichever department-head it truly concerns — that is, its direction must be correctly written. Only when it is written so does the matter reach him, and only then does he act upon it. Whether our heart's desire deserves to be fulfilled — whether we are worthy of it or not — is something we must urgently examine in ourselves. Whether the thoughts, resolves and desires within us are filled with firm faith or not will be decided by this: the touchstone is the ordained procedure established by God, and one's fidelity to it. When our resolves become firm and pure, they gain the power to draw his compassionate, gracious glance. Ritual action is, for man's advancement, the very staff of life — as vital to living as the air itself. Just as there is food to relieve hunger and water to quench thirst, so too there exists, between man and his ultimate goal, that same kind of relation through ritual action. Therefore, the observance of Veda-enjoined ritual action is our duty. There are three karmas that reach God directly: niṣkāma karma, selfless Prema, and prayer issuing from a pure heart — these alone are God's own departments. Prayers of this kind go straight to God