Can you elaborate on the concept of spiritual birth as initiated by a Sadguru, based on the descriptions in Chapter 50?

Chapter 50 presents a profound concept of spiritual birth that transcends physical reality. It contrasts the worldly father, who gives life via the 'yoni' or birth canal, with the Sadguru, who is called an 'extraordinary progenitor.' This spiritual fatherhood is a wondrous miracle because the Guru gives birth to a disciple 'without spending a drop of seed, without the lower birth canal.' This birth is facilitated by 'Anugraha,' or full initiation and grace. The ultimate purpose of this spiritual rebirth, as highlighted in Chapter 50, is to create a true spiritual heir who can transcend the endless cycle of birth and death, a feat the worldly father cannot accomplish.