The confusion surrounding the early philosophical reception of Relativity theory can be traced back to a misconception regarding the status of ‘time’ in philosophical—and possibly scientific—discourse. Bergson’s ‘quarrel’ with Einstein revolves around the possibility of apprehending simultaneity at a distance as a sheaf or envelope of durations unfolding in ‘real time’. Neither ‘proper’ time (invariant, local) nor ‘coordinate’ time (frame-dependent, global) can properly reflect the intuition of that thick present. While Bergson strives to incorporate it back into the relativistic framework based on the experience of lived simultaneity, Whitehead formalizes it in terms of ‘contemporaneous’ extended events. Yet both seek a regional understanding of the matter, in line with some contemporary philosophers of spacetime. The (in)famous twin paradox is examined in this light, along with certain critical concepts in Bergson’s philosophy of time. The challenge is to unpack the meaning of coexistence beyond the immediate phenomenological features of proximal co-presence.