Doesn't The Economist let you read four(?) articles a month without subscribing?
Anyways, here's the relevant excerpt from the HN FAQ
Are paywalls ok?
It's ok to post stories from sites with paywalls that have workarounds.
In comments, it's ok to ask how to read an article and to help other users do so. But please don't post complaints about paywalls. Those are off topic.
I'll bite because it's a reasonable question. I think linking to paywalled content is allowed because there are fairly easy ways around paywalls, but posting a roundabout directly goes (I believe) against HN policy.
An example of how to get around the Economist paywall is already elsewhere in this thread.