In the midst of the thunder in the cloudy sky there appears a rainbow that has no string. Its appearance is compared to the appearance of the Supreme Personality of Godhead or His servants in the midst of the material atmosphere.
The Sanskrit word guna means “quality” or “mode,” as well as “string” or “rope.” When a rainbow appears during the rainy season, it is observed to be like a bow with no guna, or string. Similarly, the appearance of the Personality of Godhead or His transcendental servants has nothing to do with the qualitative modes of material nature. The phenomenal appearance of the Transcendence is free from the qualities of material nature, and thus it resembles a bow with no string.
The transcendental Supreme Lord is eternally the form of transcendental existence, knowledge, and bliss. The material energy works under His good will, and therefore He is never affected by the modes of material nature. When He appears before us in the midst of material interactions, He remains always unaffected, like a stringless rainbow.
By His inconceivable energy, the Supreme Lord can appear and disappear like a rainbow, which appears and disappears without being affected by the roaring thunder and the cloudy sky. The Lord is eternally the biggest of the big and the smallest of the small. The living beings, who are His parts and parcels, are the smallest of the small, and He is the biggest of the big as the Absolute Truth, the Supreme Personality of Godhead.
Link to this page: https://prabhupadabooks.com/lob/15