What are the two different motivations for using spiritual texts like Guru biographies, as described in the source?

According to the preface in Chapter 0, spiritual texts, including Guru biographies, are utilized in two distinct ways: with desire (Kamya) and with a selfless mind (Nishkam). The Kamya approach is undertaken for worldly goals, such as attaining prosperity or seeking the removal of worries, calamities, and illnesses. In contrast, the Nishkam approach is pursued for spiritual liberation from the world and the cycle of birth and death. The text strongly emphasizes that Nishkam Guru service is always considered the superior path, regardless of the specific form of service being performed.