Like many words, secular has other senses. Per a representative definition like… http://www.merriam-webster.com/dictionary/secular http://www.merriam-webster.c

Like many words, secular has other senses. Per a representative definition like… http://www.merriam-webster.com/dictionary/secular http://www.merriam-webster.com/dictionary/secular …Feld is using the sense (3), and especially (3)(c), a quite common usage in economics (as a contrast with transient/cyclical changes). You might benefit from a more catholic appreciation of vocabulary. (And no, that has nothing to do with the Catholic church.)