The indefinite article with proper names

The indefinite article can be used with a proper name to express uncertainty about the person's identity or that the speaker does not know the person:

A Mr Smith was looking for you this morning. (Someone called Mr Smith was looking for you this morning.)

The indefinite article can also be used before a proper name to refer to the characteristic features of the person:

He was an Einstein of his time.

A proper name with an indefinite article can refer to a work of art created by the person:

He bought a Picasso at Sotheby's in 1970. (He bought a painting by Picasso.)