In part it was a result of various waves of conquest, but it also reflects concerns for purity and the fear of pollution. (religion-online.org)
Like every single tower defense game before it, Carrot Fantasy requires the player to protect a «tower» from various waves of baddies. (kotaku.com)
Despite the history of merit pay, these plans continue to be reborn, including in various waves in the United States over the past century. (gse.harvard.edu)