Every Catholic should know the Four Last Things: Death, Judgement, Heaven, Hell.
If there are 'Last Things', I would reason that there obviously should be 'First Things' as well as 'Middle Things'.
Perhaps these are the First Four Things for each of us - in the context of the spiritual life:
These "Four First Things", although not necessarily in this order, set us on the road of our spiritual life. Some (Confession and Communion) accompany us on our journey to the "Four Last Things".