Watch the Playing Over The iii Chord online guitar lesson by Brad Carlton from Guitar Lab: Thirds and Sixths

The Phrygian mode is the third mode of the major scale and it's formula is: 1 b2 b3 4 5 b6 b7. When these notes are aligned in thirds (the heptatonic arpeggio), the numbers are as follows: 1, b3, 5, b7, b9, 11, b13. Knowing this information will help you organize your thirds based upon the prevailing harmony.