-By nature I mean the essence of things or objects, in this case that of 'particle' and 'wave'.
-The general reason is of course the s.c. 'particle-wave duality'.
-The specific reason is of course this: on some time it behaves as a 'particle', at other time as 'wave'.
-Philosophically reasoned: so, not always! This implies (strong or weak in this case is undecided): the nature of 'particle' is not identical to that of 'wave'.
-Please check whether my philosophical reasoning is true or false. Thanks for your answers! Marc.