A lively and inspired talk at Stockholms Buddhistcenter in 2007, companion talk to The story of Hatthaka. (https://thebuddhistcentre.com/stockholm/story-hatthaka)
Ratnaprabha gives a good description of the 4 means of bringing together or gathering a sangha. One does this through generosity, loving (freeing, liberating) speech, beneficial activity and having or sharing the same goal.