The word focus has, as a noun, been used in the English language as far back as the early seventeenth century. Kepler, a prominent German physician, first employed it to describe the physical point at which rays of light focused after having passed through a converging lens or mirror. However, a focus can be defined generally as the converging point of several key concepts, ideas, energies or physical objects. The word was derived from its Latin counterpart of the same spelling defined as ‘hearth’, as in the hearth of a fireplace, or more loosely as family, or home. The English focus, however, was not the only word to spring from this Latin terminology; the French word foyer (of identical meaning to the English ‘focus’ defined above) also finds its roots here.
Foyer, of course, was then also adopted into the English language, albeit much later (in the first half of the nineteenth century). Foyer did not carry over its definition as a focus but instead came to describe the type of entryway commonly leading into theatres or hotels, into which people gather before proceeding further into the establishment, or equally just before leaving. The reason for which I speak to this effect is that the foyer is actually a perfect example of a physical convergence or focus of people. Interestingly enough, the same is true for the hearth described by the Latin focus.
At the time the Latin use was still relevant, city homes were generally very small, very dark, and very claustrophobic. The fireplace would have been for a large part the sole contributor of light to the house (aided only by candles and weak oil lamps), as well as the only source of heat. The family would have cooked meals over the fire contained within the hearth, ate in a joined space nearby, slept close enough to feel its warmth. In short, the hearth would have been the place in the home where a family would regularly come together; would have been the focusing point, if you will, of their at-home lives.
This relation can be extended to many modern architectural spaces in two main senses, the first being through the creation of spaces designed for people to congregate in in contrast to those meant for people to move though. A building’s energy can, with an ounce of foresight in its planning, be converged into the appropriate spaces meant to support it, leaving other areas more sparsely populated. For example at this school both the atrium floor and the studio are spaces meant to focus energy and foster it, while the staircases were built quite narrow so as to promote only the passage of persons from one of the former hubs to the other. Finally, a given building can dictate where an observer’s attention is meant to converge, for example by having a single prominent architectural detail on an otherwise flat white wall, or by facing all of a room’s seating in a single orientation so as to focus an audience’s attention towards, for instance, a speaker or presentation.
"foyer, n.". OED Online. September 2012. Oxford University Press. http://www.oed.com/view/Entry/74082?rskey=HIiA5f&result=2&isAdvanced=false (accessed November 18, 2012).
"focus, n.". OED Online. September 2012. Oxford University Press. http://www.oed.com/view/Entry/72350 (accessed November 18, 2012).