Hi, all.

I'm working on translating the Old Norwegian rune poem, and I'm stuck on
the ís verse:

Ís köllum brú breiða; blindan þarf at leiða.

I've got a passable translation for the first phrase: "Ice we call a
broad bridge". The second phrase, though, seems to me to have to be "the
blind [man] (blindan) needs (þarf) to (at) lead (leiða, inf)". I've seen
it translated as "... to be lead," but I don't know how what I'm
assuming as the infinitive form "leiða" gives us "to be..."

What am I missing?

Thanks in advance,
- sabin