It is a figure of speech called Heterosis (of Number): The plural for the singular. "This is so put when great excellence or magnitude is denoted. Our attention is thus called to the importance of the thing or matter concerning which the statement is made." - Figures of Speech by E.W. Bullinger (pg. 529)
Modern day example is a Monarch when speaking of themselves ("We, the Queen...")
It is a figure of speech called Heterosis (of Number): The plural for the singular. "This is so put when great excellence or magnitude is denoted. Our attention is thus called to the importance of the thing or matter concerning which the statement is made." - Figures of Speech by E.W. Bullinger (pg. 529)
Modern day example is a Monarch when speaking of themselves ("We, the Queen...")