This is one of four “love duet choruses” which Handel adapted from music he had previously written for two sopranos. These duets were in Italian and were of a very secular nature. The text to this one, for example, was: “Life too is a flower: it comes with the morning and dies with the spring of a single day.” The music that is now set to the word “purify” was originally sung on primavera (spring).
This chorus concludes a section in which the purifying “refiners fire” of the previous aria seems to continue to flicker and burn away human impurities, as the spirit of the Old Testament Messiah that is here referred to would do. But now, instead of the terror felt in the aria we have the hope that the “sons of Levi” (the priestly tribe of Hebrews) will offer righteousness. And by implication we, too, must make a supreme offering to bring off a “pure” performance of this difficult chorus! Use a light and buoyant tone, devoid of any ponderousness or thick singing. Make a clear distinction between the light melismas of Theme A and the sustained second theme so the contrast sets them off against each other.

Theme A – BASS, measures 5-10   (sung marked and detached in a light manner and clear tone)

            And He shall purify, and He shall purify the sons of Levi. – strong ND, SH, L’s, flip “r” on “purify”

            (EH)nd   h(EE)   sh(EH)ll   P(EE)(oo) - D(IH) - F(UH)(EE)

th(oo)   S(UH)NS   (UH)v   L(EE) - v(UH)(EE)

            emphasize beat 4 measure 6,  beats 2 and 4 measure 7. and beat 2 measure 8 of long run.

Theme B – TENOR, measures 12-15   (sung broadly and sustained)

            The sons of Levi – strong L, emphasize second beats (suspensions) of held notes

 

            Th(oo)    S(UH)NS   (UH)v   L(EE) - v(UH)(EE)

            Small chorus sing   d(oo)  d(oo)  d(oo)  d(oo)  etc. on melismas

            Bar 55 – all phrase after beat 1, final four beats  sung  sostenuto.

Theme C – ALL at “B” and “E”   (sung Legato)

            That they may offer unto the Lord an offering in righteousness – omit “r” in “offer” an “Lord”,

                        Flip “r” in “righteousness”, strong “th”s, L, deemphasize “ss” es

            Th(EH)t   th(EH)(EE)   m(EH)(EE)   (AW) - F(oo)    (UH)n - t(oo)    th(oo)    L(AW)D 

                        (EH)n    (AW) - F(oo) - R(IH)NG    (IH)n    R(UH)(EE) - ch(UH)s - n(EH)ss