The disjunction forming the title of this post is true because both its operands are true. Prima facie, it seems impossible that it should be so: for, how can any creaturely event happen spontaneously – that is to say, as a result of the free operation of a creaturely will – if Omniscience has known from before all time that the event will occur? God cannot know of a fact that is not indeed a fact; if he knows what I will do, it would seem then that I have no alternative but to do it, and am not therefore the least bit free. If on the other hand I am anywise free, then it would seem that God cannot know what I will do before I have done it.
The solution to this conundrum, as with so many theological difficulties, lies in the recollection that in the eternity that is the only coherently conceivable perspective of Omniscience, there is no before or after. Thus Omniscience and creaturely spontaneity are reconciled by means of the same method that reconciles the doctrines of salvation by election and by faith. God’s knowledge of the contingent acts of his creatures is accomplished by that same motion by which those contingent acts are effected. Thus contingent creaturely acts and God’s knowledge thereof are the same motion considered from different perspectives. The creature is what it knows it does; and God knows what the creature is.
Because in the final analysis all things take place in eternity, the creative actus purus of God, in which his own being subsists, is coterminous with the contingent acts of creatures. Note that this is to say that Divine and creaturely acts share the same ultimate terminus ad quem, the completion and integration of all things. That terminus is the Omega, toward which all beings tend, at which in their completion they arrive and are joined.
Post Scriptum: the argument of this post would work to similar effect if the operands of the disjunction that forms its seed were Omnipotence and spontaneity.
 Spontaneous comes from the Latin (sua) sponte “of one’s own accord, willingly.”