Every Ashtanga practice starts with the invocation to Patanjali, so I thought I would try to unpack the meaning of the chant here. I'm relying largely on Ronald Steiner's excellent AshtangaInfo website.
vande gurūṇāṁ caraṇāravindeLiterally, "I bow to the lotus feet of our great teachers,
sandarśita svātma sukhāva bodhe
who uncovers our true self and awakens happiness."
The great teacher is of course Patanjali, who is said to have written the Yoga Sutras about 150 BCE. It doesn't seem that anyone can clearly identify Patanjali as a historical figure and some traditions deify Patanjali as a manifestation of a God. The second line clearly refers to the third line of the Sutras: "For finding our true self (drashtu) entails insight into our own nature."
nih shreyase jangali kayamaneThis site translates this as follows:" which are the refuge, the jungle physician,
sansara halahala mohashantyai
which eliminate the delusion caused by the poisonous herb of Samsara (conditioned existence)."
Steiner explains: "The jungle shamans were the best doctors. They had huge knowledge about medicinal plants and leaves and they could heal a variety of illnesses. In India their fame exists until today."
Samsara is conditioned existence. What does that mean? The sutras say: When you are in a state of yoga, all misconceptions (vrittis) that can exist in the mutable aspect of human beings (chitta) disappear. That is, the vrittis lead to samsara and it is the practice of yoga that wipes out these misperceptions and enable true union.
Well, that's the start of the chant. More later.