The Hebrew particle aken (אָכֵן) is an adverb of strong affirmation — 'surely,' 'indeed,' 'truly,' or 'certainly.' It introduces statements of discovered truth, divine promise, or solemn confirmation.
Aken appears in moments of revelation and recognition throughout the Old Testament. Jacob awakens from his dream of the heavenly ladder and exclaims, 'Surely the LORD is in this place, and I was not aware of it!' (Genesis 28:16) — a paradigm of how God's presence is discovered in unexpected places. The word signals the dawn of understanding, the moment when the veil is lifted. Isaiah uses aken powerfully in the Servant songs: 'Surely he took up our pain and bore our suffering' (53:4) — the great 'indeed' of substitutionary atonement.