Many of Mendelssohn's letters and statements demonstrate his aversion to any music, including the traditions he encountered on his travels in Scotland and other destinations, when it stood outside certain aesthetic and technical teachings that in his student years he took to heart as universal axioms. Friction becomes evident between this rejection of rule-breaking styles and his Romantic desire to be connected to folk music, furthered by his visual and literary attraction to Scotland particularly. I argue that this cognitive dissonance spurred Mendelssohn to transform folk modality—real and imagined—into a personalized form in his work. A striking example is the “double tonic” effect associated with many Scottish modal melodies: the rapid alternation between outlined triads a whole step apart. Though this tool could potentially create the type of exoticism the composer tried to avoid in his mature work, he nevertheless later adapted the feature to articulate all the main cadential passages of his “Scottish” Symphony's first movement; but he found a way to rework the double tonic's inherent melodic dynamism into harmonic stasis, thus preserving the artistic laws he valued while creating a special sound at the same time. Inflecting some theories by other scholars on Mendelssohn's “Scottish” style(s), I examine how this and his other altered evocations of modality temper or even displace functional harmonic tension, and elements of this style permeate some of the composer's other works to become a topos. Nevertheless, the “Scottish” music, especially the Symphony, is more deeply affected than the other works—reflecting a unique set of circumstances.