It reminds me of the scene in Cecil B. DeMille’s Biblical epic “The Ten Commandments” [1] where the Israelites tramp the mud for making bricks. They tramp and complain about their lot. One of them says something about man made in God’s image when suddenly the slave master, worn out with the complaints, replies “This will change your image!” Whereupon he flings a dagger into the poor man’s chest.
Masters and slaves: components attached to an I2C bus operate either as masters, slaves or sometimes both. The designations merely apply to who initiates a communication and who replies, who asks and who answers. Normal communication always takes place between two components. Term master or slave really just defines the behaviour of the two communicating components during the communication cycle. The one that started it behaves as the ‘master’ and the one answering behaves as the ‘slave.’ Of course, at some other time in another cycle, the one asking may become the one answering. Master becomes slave! When no-one is talking, masters and slaves effectively cease to exist; masters become nominal masters because they have master potential, slaves become nominal slaves.
Note in particular that ‘master’ is not necessarily synonymous with ‘transmitter.’ A master may initiate communication but may request receiving of data rather than transmitting. Hence master may be master-transmitter or master-receiver.