"In the first place, you must pay great attention to the key note"

This quote from William Billings exhorts the value of focusing on the "key note". This phrase describes a very essential fundamental aspect of music - the pitch that forms the basis of a musical piece. It is the starting point around which all other notes and melodies are built. Taking note of the essential note is crucial for any musician - it helps them stay in tune and in rhythm with the rest of the group, and makes sure that the music is cohesive and harmonious. Billings is essentially stating that if one wants to be a good artist, they need to understand and concentrate on the fundamentals of music, beginning with the crucial note.