A critical factor in its success was that the X developers were willing to give the sources away for free in accordance with the hacker ethic, and able to distribute them over the Internet. Eric S. Raymond
Having insurance doesn't guarantee good health outcomes, but it is a critical factor. Irwin Redlener
Happiness is a critical factor for work, and work is a critical factor for happiness. In one of those life-isn't-fair results, it turns out that the happy outperform the less happy. Happy people work more hours each week - and they work more in their free time, too. Gretchen Rubin
The most critical factor subduing the demand for housing is that home ownership is no longer seen as the great, long-term buildup in equity value it once was. Mortimer Zuckerman