The phrase "wast sensible of" is an archaic form of English meaning "you were aware of." The spelling reflects the pronunciation of the time, with "wast" being the second person singular past tense of "be" and "sensible" pronounced with a long "i" sound as "SEN-si-ble." The word "of" is pronounced as "ov" with the vowel sound being a short "o" followed by a "v" sound. This spelling is a glimpse into the evolution of the English language and how it has changed over time.