Is there a limit to happiness that we can have?
Medicine says YES.
"Fine Line Between Pleasure & Pain"
http://www.scienceagogo.com/news/19990718214106data_trunc_sys.shtml
Study Shows Brain's 'Pleasure Chemical' Is Involved In Response To Pain Too
http://www.sciencedaily.com/releases/2006/10/061019094148.htm
http://www.opioids.com/dopamine/pleasurepain.html
http://www.dailymail.co.uk/sciencetech/article-1081242/Brain-line-love-hate-scientists-reveal.html
http://www.independent.co.uk/news/science/scientists-prove-it-really-is-a-thin-line-between-love-and-hate-976901.html
Taoism says that every thing in creation consists of the pairs of opposites Yin and Yang. Yin represents darkness and Yang represents light.
http://www.shen-nong.com/eng/principles/whatyinyang.html
http://www.sacredlotus.com/theory/yinyang.cfm