  Intuitively, the totality of physical reality -- the Cosmos -- has a
beginning only if (i) all parts of the Cosmos agree on the direction of time
(the Direction Condition) and (ii) there is a boundary to the past of all
non-initial spacetime points such that there are no spacetime points to the
past of the boundary (the Boundary Condition). Following a distinction
previously introduced by J. Brian Pitts, the Boundary Condition can be
conceived of in two distinct ways: either topologically, i.e., in terms of a
closed boundary, or metrically, i.e., in terms of the Cosmos having a finite
past. This article proposes that the Boundary Condition should be posed
disjunctively, modifies and improves upon the metrical conception of the
Cosmos's beginning in light of a series of surprising yet simple thought
experiments, and suggests that the Direction and Boundary Conditions should be
thought of as more fundamental to the concept of the Cosmos's beginning than
classical Big Bang cosmology.
