It is my conviction that you cannot be a good type designer if you are not a book typographer. I am not talking here about display types but about text types. A type designer must know how type works in a piece of text, he must know what happens with the type on different sorts of paper, he must know how a typeface behaves with different printing techniques.
For me the basis of all good text typefaces is writing with a broad nibbed pen. The contrasts in written characters is derived in a natural way, and it is the type designer who translates these contrasts in a printing type. It is not only the contrast that comes into being, also the widths and proportions within the characters flow from the pen. Making a seriffed typeface based on a sans serif leads to unbalanced proportions.
I am of course not saying you cannot design a sans serif without first making a seriffed typeface, there are a lot of fine sans serifs that are designed without a written base. But when a family of serif and sans serif is created it is my conviction that the seriffed version is the starting point.
–Martin Majoor