I thought I would open a separate thread on Nagarjuna so as not to distract from Retro’s question in the previous thread.
I hope this may expand the study and understanding of Nagarjuna's teachings.
I wish to recommend Causality and Emptiness, The Wisdom of Nagarjuna, by Dr.Peter Della Santina. And in particular I wish to recommend the “Good Hearted Letter” in Section I.
Here Nagarjuna presents a fine, concise, and comprehensive summary of the Buddha’s teachings.