The concentration of the tatha^gatas. The highest of the 108 degrees of sama^dhi practiced by bodhisattvas' also ca11ed 大空三昧 /su^nyasama^dhi， i.e. of the great void， or immateriality， and 金刚三昧 vajrasama^dhi （adamantine sama^dhi）. A deep state of concentration attained based on the observation of the principle that all things possess the same basic buddha-nature.