The perceptions we observe may well be coming from an artificial source. Suppose we could take our brain out of our body and keep it alive in a glass jar. Put a computer in which all kinds of information can be recorded. Transmit the electrical signals of all the data related to a setting such as image, sound and smell into this computer. Connect this computer to the sensory centers in our brain with electrodes and send the pre-recorded data to our brain. As our brain perceives these signals it will see and live the setting correlated with these.