Image credits: http://media.radiosai.org/journals/vol_14/01MAY16/SUMMER-SHOWERS-ILLUSTRATED-1990-DISCOURSE-17.htm

Yoga apart from normalizing our CDs (pranamaya kosaha) works on the Sukshma shareer to change manas from thinking to feeling and the intellect (Buddhi) evolves to wisdom (aka vivek or the power of discrimination) and the aham gets refined thus the indivdual chitta (consciousness) expands to merge with the universal. Thought credtis: http://www.daaji.org/the-evolution-of-consciousness-part-2/