Oh, yeah, think of event sourcing. You have a series of events leading up (aggregate) into some state. This can be done in different ways but with Datomic you

Oh, yeah, think of event sourcing. You have a series of events leading up (aggregate) into some state. This can be done in different ways but with Datomic you can request a point in time database. This database doesn't exist so it needs to be "sourced" from history. This means running through everything that happened up to some point to create a snapshot of the database state (or query).