Excellent summary and lead in to the continuing exploration...

Yoga is samadhi I undestand that now.  Because looking at the 8 limbs of Astanga yoga I thought for years that samadhi was the culmination of the practice of yoga.  Then again I hadn't been exposed to the YS!  But yoga is all the limbs of yoga, so samadhi resides in all of them.  Brilliant explanation, looking forward to exploring the "how to " next

In the Sāṅkhya map of reality the 3 Guṇas are not explicitly mentioned - can we assume they are part of prakṛti or do they apply to all the tattva-s on the list, or to the 5 great elements only?

Hi Caroline, we could say that the three guṇa-s inhere in prakṛti, that prakṛti is constituted of the guṇa-s. As such the three guṇa-s inhere in all the tattva-s from prakṛti to the mahābhūtāḥ