In 1918 a British High Court judge in Calcutta, Sir John Woodroffe, publishing under the name Arthur Avalon, brought out a translation of this text with a long introduction and called the book The Serpent Power. It was the first substantial and sympathetic English presentation of tantric subtle-body doctrine, and its effect was enormous and largely unintended. Nearly every modern account of "the seven chakras" (in yoga studios, in New Age literature, in popular psychology), descends from Woodroffe's book, and therefore from this one chapter by one Bengali author in 1577.
That descent has consequences worth stating. The Indian tantric traditions do not agree on a single scheme: systems of four, five, nine, twelve and more centres are attested, the placements differ, and the number six plus one is Purnananda's convention rather than a universal Indian teaching. The rainbow colour sequence attached to the chakras almost everywhere today is not in this text at all; it is a twentieth-century Western addition, spread through Theosophical writing and later through the human-potential movement. So is the association of each centre with an endocrine gland, and so is the psychological reading of the centres as stages of emotional development.
None of that makes the modern system worthless; it makes it modern. The distinction the atlas keeps is between what the 1577 text says, which is set out above, and what has been built on top of it since 1918, which is a separate and traceable history.