This article is first published in this series.
Keywords: Operad, monad, enriched category, monoidal category.
2000 MSC: 18D50, 18C15, 18D20, 18D10
Reprints in Theory and Applications of Categories,
No. 13 (2005) pp. 1-13
http://www.tac.mta.ca/tac/reprints/articles/13/tr13.dvi
http://www.tac.mta.ca/tac/reprints/articles/13/tr13.ps
http://www.tac.mta.ca/tac/reprints/articles/13/tr13.pdf