Verse 21

अभ्यासयत्नौ प्रथमं मुख्यो विधिरुदाहृतः ।तदभावे तु गौणः स्यात्पूज्यपूजामयक्रमः

In plain words

Abhyāsa and effort together are declared, first of all, the chief method; in their absence, the secondary would be the course made up of worship of the one to be worshipped.