How can studying a Guru's biography be used, and what is the difference between 'Kamya' and 'Nishkam' approaches?

The text provided in Chapter 0 explains that both knowledge texts and Guru biography texts can be used in two primary ways: with desire (Kamya) and with a selfless mind (Nishkam). The Kamya approach involves using the study of these texts for worldly gains, such as achieving prosperity or seeking relief from worries, calamities, distress, and diseases. In contrast, the Nishkam approach is performed without any selfish desire, purely for the goal of spiritual liberation from the world and the cycle of birth and death. The text explicitly states that Nishkam Guru service, whether through writing a biography or any other means, will always be considered superior.