Universal Quantification

Can someone please explain the meaning and consequences of the following 
in layman's terms:

"Also notice that the correspondence of owl:allValuesFrom with the 
universal quantifier means that an owl:allValuesFrom constraint for a 
property P is trivially satisfied for an individual that has no value for 
property P at all. To see why this is so, observe that the 
owl:allValuesFrom constraint demands that all values of P should be of 
type T, and if no such values exist, the constraint is trivially true."

Thanks,

--- Stephen