Explain why transitory thinking is described as affecting the constancy of individual thoughts, rather than the broader continuity or organisation of the whole train of thinking.

This distinction separates transitory thinking from other formal thought disorders that instead affect how successive thoughts connect to one another across a longer stretch of speech. In transitory thinking, the problem occurs within a single thought or sentence, whose constancy gives way partway through, producing a grammatically disrupted shift onto unrelated content, rather than a broader failure of the logical or associative links between one complete thought and the next. Recognising that the disturbance operates at this narrower, within-thought level, rather than across the wider organisation of a train of thinking, helps distinguish transitory thinking from disorders such as desultory or drivelling thinking, which instead concern how separate ideas or the parts of one larger thought relate to each other.