Riley reports on one study that found that between 1991 and 2006, immigrants started an amazing 25 percent of all U.S. public companies that were backed by venture capital, and these companies' market capitalization exceeded a half-trillion dollars. And the foreign-born swell our engineering, science, computer, and math programs at the undergraduate and graduate level, as well.

Riley also tackles the myth that immigrants aren't assimilating -- a misconception I've been fighting for years, as he generously acknowledges. Today we worry about Mexicans and Guatemalans, but not so long ago it was Germans, Italians, and the Irish who we were sure would never become Americans. As Riley points out, the Irish immigrants of the 19th century (my great-grandparents Michael McKenna and Catherine Dolan among

them) were "dirt-poor peasants back home. ... Most were uneducated. Many spoke no English. ... They were stereotyped as slow-witted drunks and ne'er-do-wells who would never acculturate to America."

Yet they did become Americans -- as has every group, no matter where they came from. That is the wonder of America, that we can transform the most unpromising of newcomers. And within a generation or two, they are indistinguishable in all important aspects from those whose families have been here since the founding.

We shouldn't give up on this great American ideal. Ronald Reagan certainly never did.