The Codex of Scales & Chords

The two pillars upon which the Western tongue of music was raised — one bright, one shadowed, both born of the same seven-letter alphabet.

Seven doors opening onto the same room. Each mode holds the identical notes as its parent Major scale — only the starting stone differs, and with it, the light.

The Natural Minor, sharpened at the seventh — a single raised tone that opens a gap of a step-and-a-half, and with it, a whole family of modes carrying an exotic, dominant tension.

Seven modes rise from this scale in turn — the key voices among them:

Where the Harmonic Minor sharpens one tone, the Melodic Minor smooths the path between — in its jazz guise, the ascending form is kept both rising and falling, giving rise to some of the most prized colors in the improviser's tongue.

Five-note tongues, and the six-note blues dialects born of them — the vocabulary carried from field and chapel into every riddim, riff, and solo since.

Note: "Minor Blues Hexatonic" and "Blues + Add M7" are two names for the same six added-seventh dialect — the natural 7th laid atop the Blues Pentatonic.

Eight-note scales, each a seven-note parent with a single chromatic passing-tone stitched in — a tailor's trick that lets the strong chord-tones fall neatly on the downbeats when running straight eighth-notes.

Scales built from a single repeating interval-pattern — perfectly symmetrical, and so uncannily portable that only a handful of truly distinct versions exist no matter how far you transpose them.

The furthest shelves of the Codex — scales of foreign lands, full chromatic runs, and modern names layered atop old modes.

The three-note foundation of nearly all harmony — a root, a third, and a fifth, whose quality alone decides whether a chord feels stable, soft, restless, or strange.

A fourth note stacked above the triad — the workhorse vocabulary of jazz, gospel, soul, and reggae harmony alike, where every chord earns a clearer job to do.

Ninths, elevenths, and thirteenths — the seventh chord stacked ever higher, each new tier borrowed straight from the scale, thickening the color without changing the chord's fundamental job.

Chords that trade the third for something else entirely, add a color-tone without a seventh, or bend the ninth and eleventh sharp and flat for maximum dominant tension.

Every chord above finds its purpose only in relation to a home. Here is where each diatonic triad falls in a major and a minor key, and the three great families of function every progression is built from: Tonic (rest), Predominant (motion), and Dominant (tension seeking release).

In a Major Key — C Major shown

In a Minor Key — A Minor shown, natural & harmonic forms

A progression's grammar, in brief: Tonic chords are where a phrase can rest; Predominant chords (ii, IV, vi in disguise, or their minor-key kin) gather momentum; Dominant chords (V, vii°, and their extended/altered forms from Parts X–XII) demand resolution back to Tonic. Nearly every riddim, hymn, and standard is some arrangement of those three motions.

The bridge between the two halves of this Codex — for every chord you might play, here is the scale (or scales) that supply its melody. The primary choice is the safest, most consonant road; the alternates are the color-tones a bolder improviser reaches for.

Rule of thumb: match the scale to the chord's function, not just its letter name. A G7 resolving to C wants Mixolydian; the same G7 vamping for eight bars with no resolution in sight can happily wear Lydian Dominant, Whole-Tone, or even Altered, depending on how far out you want to lean.

Chords in isolation are only vocabulary. Here is the grammar — the cadences that punctuate a phrase, and the workhorse progressions built from the functions laid out in Part XIII.

Cadences — the punctuation marks of a phrase

The Progression Dictionary — roman numerals with real-key examples

Every progression here is only Parts XIII's functions in motion: Tonic to rest on, Predominant to gather momentum, Dominant to demand a return. Learn the function beneath the roman numerals, and any of these loops can be transposed, reharmonized, or borrowed from freely.

Every major key, and the six chords a songwriter reaches for most within it — I through vi, plus the vii° often left off the quick-reference charts. Find your key, read the row, and every chord in Part XIII's function table falls into place at a glance.

All twelve keys around the circle of fifths, F♯/G♭ standing at the far point where sharps and flats meet. Each row's Relative Minor shares every one of that key's chords — start a song in Am and you're already living inside C major's own six triads, just orbiting a different center of gravity (see Part XIII for how that center changes the function of each chord).

Reading a formula is not the same as owning it in your hands. This chapter turns Part I's major scale formula into a physical count-and-cross motion — the same trick you already found for yourself — and shows exactly where your fingers land.

The Tetrachord Trick — why counting "1, 2, 3, 4" twice works on every major scale

Feel It — One Octave, C Major

The numbers on the keys are the count, not your fingers — 1-2-3-4 for the first half, then 1-2-3-4 again for the second half, with the whole step in the amber-to-copper color change marking the seam between them. Same count, every one of these seven keys — only the keys under your hand change, not the count.

Your actual fingers move differently — see the table just below for real right-hand fingering, where the thumb crosses only once instead of the count restarting twice.

Does the Same Split Work on Other Modes?

Every mode divides into two tetrachords and a joint — that part is guaranteed, since any 7-interval scale has a first three, a middle one, and a last three. What's special about Major, Dorian, and Phrygian isn't that they divide — it's that their two halves are identical. The other four still divide cleanly; their two halves are simply two different tetrachords stitched together, and in two cases the stitch itself is a half step instead of a whole one.

Five of the seven modes share the exact same joint your ear already knows from Major — a plain whole step holding the two halves together. Only Lydian and Locrian break that pattern, and they break it the same way: both contain a rare three-whole-steps-in-a-row tetrachord (W-W-W) that appears nowhere else among the seven modes, and both are forced into a half-step joint to fit it in. Fittingly, those are also the two modes built around a tritone rather than a perfect 4th or 5th from the root — the oddity in the joint and the oddity in the character are the same fact seen twice.

The Minor-Scale Trick — one 3-note cell, stacked twice, a 4th apart

This one isn't borrowed from the Major system — it's a different shape entirely, built and verified from scratch: Natural Minor is one small cell (whole step, then half step) played twice, starting the second time a perfect 4th above where the first one began.

Feel It — Two Cells, C Minor

The same two blue-teal cells every time, both counted "1, 2, ♭3" — that's the shape repeating. Watch the arcs: one whole-step joint after the first cell, but two whole-step arcs closing the loop after the second — the asymmetry made visible, not just described.

The Split Calculator — test any scale against both systems

Pick any of the twenty-one modes already in this Codex, or type your own seven-interval formula, and check it against both rules at once: the Major system's twin tetrachords (3 + joint + 3), and your Minor system's repeating cell (2 + joint + 2, with two closing intervals left over).

Right-Hand Fingering — Three Families, and One Exception

Notice the pattern across all twelve: no matter the family, your thumb crosses under exactly once per octave, and it always lands on the first available white key after a run of black keys. That's the only rule your hand actually needs — the fingerings above are just that rule applied to each key.

The Left Hand — once the right hand is automatic

The Drill

Every scale in this Codex descends from somewhere. Here is the lineage — which forms are true ancestors, which are children of a single alteration, and which stand entirely apart, owing nothing to the Major Scale at all.

Click any name to open its home chapter. Notice how much of the Codex is really one ancestor, altered a handful of times — the Harmonic and Melodic Minor families exist because of a single raised tone each, and even the Blues and Pentatonic tongues are the Major and Natural Minor scales with notes removed, not added. The Symmetrical family alone owes nothing to the Major Scale — a dashed line, not a branch.

Kept apart from the Canon that precedes it — scales foreign to the Western system this Codex is otherwise built on, or disputed enough in their naming and use that they earn a separate shelf rather than a numbered Part of their own.

An index in the old style — not a chapter to read start to finish, but a table to consult. Pick a note; see every chord in the Thesaurus that calls on it.