A core problem in the study of early Buddhism is the relation between dhyana and <answer>insight</answer>. Schmithausen, in his often-cited article On some Aspects of Descriptions or Theories of 'Liberating Insight' and 'Enlightenment' in Early Buddhism notes that the mention of the four noble truths as constituting "liberating <answer>insight</answer>", which is attained after mastering the Rupa Jhanas, is a later addition to texts such as Majjhima Nikaya 36.[page needed]
A large problem in the study of early Buddhism is the relationship of dhyana and what else?
insight