Hill speculates that the verse could actually be a mistranslation of Isaiah 61:1, and should have read "only the contrite will see God".

[1] The form – "blessed" (Greek: makarios) + subject + "that" (hoti) + cause – can be found in Genesis 30:13 (also in Tobit 13:16), whereas the eschatological orientation is similar to Daniel 12:12 (also 1 Enoch 58:2–3).

[2] The Greek word makarios cannot adequately be rendered as "blessed" nor "happy", as it is rather 'a term of congratulation and recommendation',[3] that can also mean "satisfied" (as in Psalm 1:1).

At the time the heart was literally seen as the seat of emotion and the soul, though today the verse is read metaphorically.

[6] Glossa Ordinaria: Purity of heart comes properly in the sixth place, because on the sixth day man was created in the image of God, which image was shrouded by sin, but is formed anew in pure hearts by grace.

So far as any one has rescued himself from evil, and works things that are good, so far does he see God, either hardly, or fully, or sometimes, or always, according to the capabilities of human nature.

[6] Augustine: No one seeing God can be alive with the life men have on earth, or with these our bodily senses.