 To remember, roughly, is to represent something that is no longer the case. On the standard taxonomy, there are three types of memory. Nondeclarative memory involves mental content that is not consciously accessible, such as one’s memory of how to ride a bike. Semantic declarative memory involves mental content that are propositional and not first-personal, such as one’s memory that Taipei is the capital of Taiwan. Episodic declarative memory involves mental content about one’s own past, such as one’s memory of the birth of one’s child. (See the entry on  memory  for a detailed discussion of this taxonomy, and especially the criterion of episodicity.) In situating imagination in cognitive architecture, philosophers have typically focused on similarities and differences between imagination and episodic declarative memory.