[+dyn] SoAs […] necessarily involve some kind of change, some kind of internal dynamism. This dynamism may consist in a recurrent pattern of changes all through the duration of the SoA, or in a change from some initial SoA into some different final SoA. [+dyn] SoAs may be called “Events”. The following predication describes Events: (4) a. The clock was ticking b. The substance reddened c. John opened the door […].
- Dik (1989), a pag.91

Vendler [Vendler, 1967, Linguistics in philosophy, Ithaca, NY, Cornell University Press] argued on linguistic grounds that a distinction should be made between “events” (our SoAs) and “facts” (our PFs). SoAs are second-order entities which can be said to occur, take place, begin, last, and end; they can be perceived: watched, heard, felt, etc.; and they can be said to be sudden, gradual, violent, etc.
- Dik (1989), a pag.248