The pay that a worker can receive for their labour is limited, at the upper end, by the value of what they produce.

FORBES: Bill Clinton Fails the Green Jobs Test

Assuming a company will grow like Google and have margins like Apple is, by definition, optimistic and this value would be at the upper end of my range.

FORBES: Facebook's IPO: Thoughts On Momentum, Pricing And Valuation (It's Still No Buy)

Under the Obama plan there is no upper limit on this loan-to-value ratio.

MSN: Housing plan details which borrowers get help

Another reason is Chinese upper middle class use real estate as a store of value.

FORBES: China Housing Bubble Up, Up And Away

The amount by which the value of a coin could vary had an upper and lower limit.

ECONOMIST: The lessons of sound money from 1,000 years' experience

Having worked their way into the upper reaches of the occupational scale, and taken note of how much the professions value abstract thinking, Asian-American parents have evidently made sure that their own children wore scientific spectacles.

NEWYORKER: None of the Above