Through certain yogic practices one can prolong one’s life and master super human and miraculous powers. But, says Nanak, these do not necessarily win God’s goodwill, without which all is vanity. In fact, in a later stanza 29, Nanak unequivocally states that such supernatural powers, more often than not, become hindrances in the way of full realisation of God.
Stanza VII
If one could extend one's life to four ages,1 nay make it ten times longer; if one were known throughout the nine planes of creation; and everyone therein followed him in respect; if every creature praised him to the sky: All this and more has no value if God’s eye looked not kindly upon him: Without His goodwill, he will be reckoned as the meanest worm amongst worms; and sinners shall charge him with sins. Oh Nanak, He bestows virtues on those who have none, and adds to the store of the virtuous. But there is naught that can bestow aught upon Him.
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Explanation: 1) Nanak here is referring to the ancient Indian doctrine of the four Yugas or cycles of time, which somewhat parallels the Western belief in the Golden Age, the Silver Age, the Bronze Age and the Iron Age. Nanak makes frequent use of such concepts and doctrines from ancient Hindu lore; but He refers to them not in a spirit of scientific truth, but often as a Divine poet, who employs allusion and mythology to drive home His point.