Spring, Summer, Autumn, Winter. Autumn, the transition from Summer to Winter. To most, it means the gradual cooling of weather, shorter daylight duration and change of lush greenery to vibrant golden yellow forests. To others, it marks the bygone days of youthful summer and nearing winter chill. Indeed, the transient nature of all things takes many forms.
This notion of transience is deeply ingrained in Japanese culture. In the case of koshirae, one can see these explicit examples - motifs of the sakura flowers (Spring), peach blossom (Summer), maple leaves (Autumn) and more subtle forms - gradual aging of patina on soft metal koshirae.
The onset of autumn also brings an interesting phenomena - iaidokas swap out zinc-aluminum iaito for shinken (if they can), collectors bring out koshirae (e.g. tsubas, menuki, etc.) for inspection and viewing. The lowered humidity is conducive for these activities.
What does that mean for iaidokas in the tropical regions? Simply more care and attention to koshirae. But, even as one toils constantly on koshirae maintenance, recognize and appreciate the transient nature of all things, including one's self.