Yagya is a means of interchange between the human and the divine powers. Whatever is given to the Divine, in whatsoever form and name, is returned back assuming a new divine quality. But this giving has to be in freedom and gladly, then only it has a true value for the spiritual purposes. By giving something willingly to the Divine we actually increase its value. Thus, for example food offered inwardly to the Divine becomes Prasad. Water offered to the Divine becomes charanamrit. The idea behind yagya is that nothing belongs to us as a separate entity. It belongs to God. That is how Sri Krishna describes it. The principle is that we offer everything to the Divine and then it is He (or when we worship a Deity) who decides whether or not to grant the abhista (the desired object). It is also that by giving we become ready to receive creating space within us.
So you see it is not the gods wanting anything for their own sake. It is rather to make sure that we are ready to receive what they can give us. In the story of Sati, Shiva can grant the boon of freedom from Ignorance. So Daksha’s refusal to invite Shiva implies that as the Prajapati he does not want those desirous for Moksha or freedom from ignorance to escape his laws. It is not only unreasonable but detrimental to progress. Hence Daksha must go and Sati’s throwing herself into the yagya fire is a symbol of sacrifice of Prakriti hoping her Lord to come.
Affectionately,
Alok Da
