has an/the ability to do sth

[joham]

Andropov has an ability to put people at ease, even those who might fear him.

Dictionaries say 'have the ability to do sth' But I read the above sentence in the TIME MAGAZINE CORPUS. I wonder if there's any difference between 'have an ability to do sth' and 'have the ability to do sth'.

Could I ask native speakers to help me please? Thank you in advance.

[Barb_D]

You may use "an" it if you think this ability is relatively unique. "The ability to..." means most people are familar with this capability, but "an ability to..." means you are definiing this strenght for people with the words that follow.

The only other difference to me is that when you use "has an ability to..." you may be subtly stating that it is one of at least a few strenghts this person has.