Associative indexing, the basic idea of which is a provision whereby any item may be caused at will to select immediately and automatically another. This is the essential feature of the Memex. The process of tying two items together is the important thing.

The question of whether a device will come into being depends upon three things: first, whether there is a practical use for it that warrants its development and manufacturing costs; second, whether the laws of physics applying to the elements available for its design allow the attainment of the needed ranges, sensitivities, or the like; and third, whether the pertinent art of manufacture has advanced sufficiently to allow a useful embodiment to be built successfully.

Fear cannot be banished, but it can be calm and without panic; it can be mitigated by reason and evaluation.

A record, if it is to be useful to science, must be continuously extended, it must be stored, and above all it must be consulted.

The summation of human experience is being expanded at a prodigious rate, and the means we use for threading through the consequent maze to the momentarily important item is the same as was used in the days of square-rigged ships.

There will always be plenty of things to compute in the detailed affairs of millions of people doing complicated things.

To pursue science is not to disparage the things of the spirit. In fact, to pursue science rightly is to furnish the framework on which the spirit may rise.