From the CCC

Nothing exists that does not owe its existence to God the Creator. The world began when God's word drew it out of nothingness; all existent beings, all of nature, and all human history are rooted in this primordial event, the very genesis by which the world was constituted and time begun. (338)

Great post. It puts it all into perspective. Creation happens at every instant simply because it all remains in the attention of the Creator. When He stops intending something's existence, that existence ceases. Thankfully, the Divine Attention never wanes.