According to the preface, what are the two ways one can use spiritual texts like Guru biographies, and which is considered superior?

Spiritual texts, such as Guru biographies, can be utilized in two distinct ways: with desire (Kamya) or with a selfless mind (Nishkam). As explained in Chapter 0, the 'Kamya' approach is for worldly purposes like achieving prosperity or seeking relief from worries, calamities, and diseases. The 'Nishkam' method, however, is pursued for liberation from the world and the cycle of birth and death. The text is unequivocal in stating that Nishkam Guru service, regardless of its form, will always be considered superior to service performed with worldly intentions.