I addition to what has been said I would also like to point out that Geometry began as a tool for construction. When building, almost all corners are right angles. In other words a 'normal' corner is a right angle. When you think of it in these terms the common usage of the word normal is a metaphor. For example, "I normally get chocolate ice cream" could be phrased "I build walls at right angles with about the same frequency as I choose chocolate ice cream".

I addition to what has been said I would also like to point out that Geometry began as a tool for construction. When building, almost all corners are right angles. In other words a 'standard' corner is a right angle. When you think of it in these terms the common usage of the word normal is a metaphor. For example, "I normally get chocolate ice cream" could be phrased "I build walls at right angles with about the same frequency as I choose chocolate ice cream".

I addition to what has been said I would also like to point out that Geometry began as a tool for construction. When building, almost all corners are right angles. In other words a 'normal' corner is a right angle.

I addition to what has been said I would also like to point out that Geometry began as a tool for construction. When building, almost all corners are right angles. In other words a 'normal' corner is a right angle. When you think of it in these terms the common usage of the word normal is a metaphor. For example, "I normally get chocolate ice cream" could be phrased "I build walls at right angles with about the same frequency as I choose chocolate ice cream".