This is crafted from the perspective of the first half of the 20th century. It is a male, Continental European perspective. This can be perceived as a bias, or simply as a legitimate point-of-view with distinguishable limitations. This is an intentional effort. He was fluent in both German and French and these languages were used extensively in the creation of this gigantic book. Readers should be aware that the influence of this has been greatly mitigated for North American readers by the translations into English. The translations were performed by two individuals, one who handled the French, and one who took care of the German.