vSphere PortMirror: What does "Source/Destination" mean as in "Remote Mirroring Source" and "Remote Mirroring Destination"?

The following is from vSphere's admin doc:

To begin a port mirroring session, you must specify the type of port mirroring session.

Procedure

1. Browse to a distributed switch in the vSphere Client navigator.

2. Click the Configure tab and expand Settings.

3. Select the Port mirroring option and click New.

4. Select the session type for the port mirroring session.

   Option	Description
   Distributed Port Mirroring	Mirror packets from a number of distributed ports to other distributed ports on the same host. If the source and the destination are on different hosts, this session type does not function.
   Remote Mirroring Source	Mirror packets from a number of distributed ports to specific uplink ports on the corresponding host.
   Remote Mirroring Destination	Mirror packets from a number of VLANs to distributed ports.
   Encapsulated Remote Mirroring (L3) Source	Mirror packets from a number of distributed ports to the IP addresses of a remote agent. The virtual machine’s traffic is mirrored to a remote physical destination through an IP tunnel.

5. Click Next.

Every time I read this part I would be confused. I could never relate the word "Source" and "Destination" to what it says in the Description and so I could never remember who's who.