When we say “yes” to what is, rather than being in denial, we know the Truth that sets us free.
Middle English ȝeis, from Old English ᵹēse ‘so be it’ and sīe ‘may it be so’, from the optative PIE stem *si- (expressing wish or desire) of the PIE base *es-, the root of is, prefixed with the PIE base *i-, *yam-, pronominal stem, also the root of Swedish ja. See also is and satsang.