There are two sorts of truth we find in our Shâstras, one that is based upon the eternal nature of man — the one that deals with the eternal relation of God, soul, and nature; the other, with local circumstances, environments of the time, social institutions of the period, and so forth. The first class of truths is chiefly embodied in our Vedas, our scriptures; the second in the Smritis, the Puranas. etc. We must remember that for all periods the Vedas are the final goal and authority, and if the Purânas differ in any respect from the Vedas, that part of the Puranas is to be rejected without mercy. We find, then, that in all these Smritis the teachings are different. One Smriti says, this is the custom, and this should be the practice of this age. Another one says, this is the practice of this age, and so forth.
This is the Âchâra which should be the custom of the Satya Yuga, and this is the Achara which should be the custom of the Kali Yuga, and so forth. Now this is one of the most glorious doctrines that you have, that eternal truths, being based upon the nature of man, will never change so long as man lives; they are for all times, omnipresent, universal virtues. But the Smritis speak generally of local circumstances, of duties arising from different environments, and they change in the course of time. This you have always to remember that because a little social custom is going to be changed you are not going to lose your religion, not at all. Remember these customs have already been changed (III, 173)
In this lecture Swamiji reminds his listeners that material spiritual co exist harmoniously “Each one of us will have to believe that everyone else in the world has done his work, and the only work remaining to be done to make the world perfect has to be done by himself. This is the responsibility we have to take upon ourselves”