至大 is read as しだい (shidai) and means immense.
しだい
shidai
だいじにいたる
to develop into a serious incident
だいしきゅう
as soon as possible
しきゅう
urgent
いたるところ
everywhere
いたる
in the extreme case of
しふく
beatitude
しじょう
supremacy
いたって
very much
しなん
most difficult
しじょうめいれい
unconditional command
しごく
top
しせい
sincerity