Although Sidney Bechet was the first to be prominently featured on the soprano sax, it was Steve Lacy who gave the soprano a home in modern jazz. Unlike many of his peers, he managed to sidestep the complexities of bebop and hard bop. He went directly from Dixieland to more progressive and avant-garde styles of jazz.
Even though this version of the song is credited as "Softly, as in a Morning Sunrise," there is actually a new melody written for the A sections of the first chorus, but the B section, however, does contain the original melody. Therefore, this version of the song is only a partial contrafact. Contrafact is a term coined by David Baker which describes when a new melody is written on a pre-existing set of chord changes. This practice was used quite commonly during the bebop era. The other method of interpreting standard repertoire is through the use of a composition technique known as reharmonizing. This is when you take a pre-existing melody and set it to a new harmonic structure.
The band does, however, play the original melody during the first two A sections on the head out, performed in the contrapuntal Dixieland style, before returning to the contrafact melody for the last A section.
The improvised solo:
First two A sections
As shown in the transcriptions below, Lacy's solo is pretty diatonic. For the first two A sections, he primarily improvises of the progression C min / Dmin7(b5) G7(b9) using the tonic harmonic minor scale; however, using the scale's flatted 6th and major 7th, sparingly.
In fact, the only non-diatonic note used is the sharp 4. And this is primarily used in the context of blues, as shown on bars 6, 8, 9, and 10. This is very idiomatic for this period. Scales like the dorian, mixolydian, and the multiple variations of the bebop scales, were more of a modern jazz phenomenon. Players from this era kept it pretty bare bones. Much of their improvisational acumen was demonstrated through their inventiveness with melody, rhythm, the blues, and often times, awe-inspiring dexterity on their instruments.
During the first two bars of the B section, when it modulates to Eb major, Lacy improvises on the major scale of the chord, also known as the Ionian mode. In the 4th bar of the B section, he plays F harmonic minor on the E dim. Players often play a G min7(b5) C7(b9) instead of the E min in order to create a more interesting harmonic motion, thus, create more possibilities during their improvisation. Using the Roman numeral analysis, it would be the #I dim substituted by the ii7(b5) and its related V7(b9).
Last A section
In the first bar of the last A, Lacy emphasizes the major 7th, which at first creates a lot of tension, but resolves smoothly to the tonic. From there, he continues playing over the C minor using the harmonic minor scale.
The transcription of Lacy's solo appears in concert, Bb, and Eb keys.