E = mc2.
Do you consider mass a priori?
No.
Mass is a property of a three dimensional world
Not true.
An equation created mass - so Einstein created mass - it is amazing that we existed before the creation of mass. You claim mass is not a proir - ok - what created mass...how did the property come into existence? You also claim mass is not a property of a three dimensional world - are you claiming there are one or two dimensional worlds with mass? Where? Show me. Buggs Bunny lives in a two dimensional world - but I think that is imaginary.