The "Golden Ratio Typography" page this post links to claims that the ideal width of a line of text is equal to the square of the line height. It does not give

The "Golden Ratio Typography" page this post links to claims that the ideal width of a line of text is equal to the square of the line height. It does not give any justification for this claim. This implies that doubling the line height should result in quadrupling the line width, which sounds dubious.