Slonimsky’s Thesaurus catalogues symmetric scales patterns and gives harmonic ideas to go along with them. These are explained in the Schillinger System of Musical Composition. What we mean by symmetric scales is scales that have multiple tonics and these tonics are created by the splitting the octave into equal sections. The first scales Slonimsky shows are Two Tonic scales. Splitting the Octave into two equal segments.
Let’s take a look at Slonimsky’s Thesaurus and understand his nomenclature. Let’s look at the chart below: