The trishula represents all the philosophical threesomes:
sat cit ananda (being, consciousness, bliss);
iccha, jnana, kriya (will, knowledge, action);
siva and shakti and the dance of relationship between the two.
The me and the you and the us–for where there are two ones there is also the third and all the play (lila) and pulsation (spanda) that is part of the dance cosmic and divine and personal.