[翻譯]Arthur Cayley，矩陣理論紀要(A Memoir on the Theory of Matrices)，part: 7

1. For conciseness, the matrix written down at full length will in general be of the order 3, but it is to be understood that the definitions, reasonings, and conclusions apply to matrices of any degree whatever. And when two or more matrices are spoken of in connexion with each other, it is always implied (unless the contrary is expressed) that the matrices are of the same order.

1. 為簡明起見，所有完整寫出的矩陣均以3階為限。但請注意，所有定義、論證以及結論，完全適用於任意階數的矩陣。另外，在論及相關聯的兩個或更多矩陣之際，我們總是假定這些矩陣的大小是相同的(除非特別聲明例外)。