Truth in Yoga ?

Some of the older yoga books talk about abstinence in both thought and action. Without the abstinence, any progress in Yoga is difficult
Often the word virya – ( sperm ) is used
Some other books describe a method called vajroli where they talk about pulling up sperm back into spinal cord , converting it into light and reaching perfection
Of course there is little merit in some of the ridiculous methods as described above
So did the gurus lie? Mislead us ? Were they stupid? Or are we stupid and just did not grasp the abcd of spirituality?
Personally I believe we are in general stupid. What they said and what we understood has a vast chasm.
In my previous blogs I have talked about the story of Vasistha and durwasa. Similarly told stories exist about Krishna as told by yogananda
These stories talk about a different method of chastity
Finally in saundarya Lahiri by Vishnu tirthji there is a more clear explanation and reconciliation between the two opposite view points. Another book has explained it more perfectly in another dimension
But reading this and understanding this is of little benefit unless you have a Guru who can open these yoga gateways