Dating a Schreiner letter

How to date a letter, which has no date on it?  Sometimes this is straightforward because of specific content (e.g. New Year’s Day and here are my resolutions, President Kennedy was assassinated yesterday).  Sometimes there is an address which can be related to a particular period of time in a person’s life . Sometimes there are things about specific content, which mean that a kind of triangulation exercise can be carried out. Such is the case with a recently turned up Schreiner letter. She writes that she had returned from Britain, she had visited her mother in Grahamstown, she was planning to spend a period of time in WagnersKraal, and she was writing in Matjiiesfontein and should the friend she was writing to come and visit.. But alas what results is not very specific. A period of some months can be identified in 1892, not a more detailed date than this. But, regardless, what comes through strongly is the passion with which Olive Schreiner was engaged in writing, and the whirlwind of emotions that her friendship with Mary Sauer brought with it.