The Whetstone of Witte by Robert Recorde (1557) Recorde’s algebra text where two equal parallel line segments as the symbol for equality was used for the first time: “bicause noe 2 thynges can be moare equalle”. 
[via Whetstone of Witte]

The Whetstone of Witte by Robert Recorde (1557) Recorde’s algebra text where two equal parallel line segments as the symbol for equality was used for the first time: “bicause noe 2 thynges can be moare equalle”.

[via Whetstone of Witte]