The sciences propagated by the Vedic rishis were given in the form of shrotras in Satyug, in the form of smritis (memories) in Tretayug, in the form of puranas in Dwaparyug, and finally as tantra and yog in Kalyug. The above presentation of the same knowledge in different forms is indicative of the constantly changing aspect of the manifested creation. As we are witnessing the last phase of Kalyug, we are experiencing things which have never ever happened before in manifested creation...to a sadhak my point should have been clear by now. For the normal householder I shall elaborate further.
In no yug has mankind witnessed the sale and purchase of the revered sciences. If Guru Drona did not want Ekalavya as his shishya then he did not; Ekalavya had to pay with his thumb for acquiring gyan through deceit. If Parashuram chose that Karan would lose the gyan given by him at the time when he would need it the most, then no force could save Karan. This was the power and ability of the Guru. No amount of wealth, I am sure, could have changed Parshuram’s or Guru Drona’s mind! This last phase of Kalyug is witnessing a phenomenon that is unique to it . Aspects of yog and tantra are being sold and bought in the open market . And like the theory of demand and supply, the meeting point of the two curves of demand and supply determines the price! You can imagine the oversupply by the fact that in mere Rs. 200 you can have your energy centres corrected - having no bearing to the karmas you have done and just Rs 600 can get you a certificate of being a yoga teacher .
I remember the words of Sir John Woodroffe here. He said that in earlier times, the Gurus had just around 15-20 shishyas to whom they had given the Shaktipath , now-a-days some Gurus give Shaktipath to thousands of people or more . These Gurus must be super beings for surpassing the ancient masters’ strengths and abilities, because one Shaktipath takes away a significant amount of the life force from the giver, and it takes long hours of practice to regain that force. It is a mystery how so many can be given Shaktipath at the same time . I hope I have triggered the thought process of the reader....