An interview with Seth Godin -
SquidU : Profiles: "Sq: What do you try to accomplish with your lenses?
Se: The same thing I try to accomplish with my writing. To give people a tiny bit of insight, to trigger a new thought that changes everything. I think that's how you deliver meaning.
Sq: How often do you try to update your lenses?
Se: I think it depends on the topic. Some lenses ought to be able to go a month without an edit, while I intend to improve and update my personal lens at least twice a week.
Sq: What characteristics do the best lenses share?
Se: Lenses are a place that people start, not where they end up. So the best lenses aren't deep or difficult... they are wide and obvious and give you a good place to dig in and start."
1. Lens are developed to serve as inspiration.
2. Update your lens as much as your blog - add, delete, shift around.
Doesn't mean you can't inspire people to buy your product - and improve their lives in the process.