the little wheel is a combination of the major scale modes and the melodic minor modes.  As such it is a diagram consisting of 14 modes interconnected such that only one accidental serves as a link between any two modes.  This is designated as a wheel and not a full loop given the fact that the Lydian augmented and the altered modes only have one link going into them and thus one cannot loop around when accessing those modes.

As seen in the studies on the little wheel, a linear progression through this loop sounds terrible because it would involve alternating between the major and melodic minor modes one after the other for a very unmusical effect.  Thus rather than using the little wheel as a vehicle for composition, it serves to show or start to show the unifying characteristics of all scales in so much that we can connect the major scale and the melodic minor scale through a series of singular jobs, singular links.  Furthermore, when we map our notes from accidental space into notes we see that the major scale is in the key of C and the melodic minor scale is in the key of G.  This is because having each link represent a perfect fifth will keep the major scale in key as well as keeping the melodic minor scale in its own key as well.  This is a condition we call Super-Diatonic and refers to the notion that all scales interconnected in a accidental diagram are in key within their respective scales.