From the time capsule

Anyone working in the photographic field who appreciates the need for moving out of the nineteenth into the twentieth century … out of the craft approach and into technology … should read, master, and keep this book in his personal library. Any serious photographer who does not know the essentials of at least the first five chapters of Photographic Sensitometry is working in the dark and risks obsolescence by not utilizing the capabilities of his medium.

Flap copy to Photographic Sensitometry by Hollis N. Todd and Richard D. Zakia, 2nd edition, March, 1974.

That the tone reproduction methods of Chapters V and XIII are thus incomplete (although sound in principle) indicates that a great amount of theoretical and experimental work is yet to be done. That the methods have been explored even to this extent only for pictorial photography suggests the need for applying them to other photographic imaging situations. Photographic sensitometry is, like other technologies, in the process of rapid change. Far as we have come in a century, the next century will surely take us unimaginably farther yet.

Final paragraph of the same.