Should a logo be self-explanatory? It is only by association with a product, a service, a business, or a corporation that a logo takes on any real meaning. It derives its meaning and usefulness from the quality of that which it symbolizes.
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The role of the logo is to point, to designate-in as simple a manner as possible. A design that is complex, like a fussy illustration or an arcane abstraction, harbors a self-destruct mechanism. Simple ideas, as well as simple designs are, ironically, the products of circuitous mental purposes. Simplicity is difficult to achieve, yet worth the effort.
— Logos, Flags and Escutcheons, Paul Rand
I love that last sentence (emphasis mine). There’s so much in that article that relates to design in general, but that one held my attention for awhile.