I would also add this: don't join a priesthood.<p>In other words, keep your mind open. Don't become a domain expert, as advised, and then convince one's self that that domain is The One True Path. Conversely, don't glance at a particular domain, assume that casual knowledge to be canonical, and then write off that domain as A Path of Fools.<p>Young programmers are especially susceptible as the myopia of youth prevents one from grasping the miniscule nature of their own knowledge. Once one gets a bit older, he/she tends to realize that what they know is but of grain of sand in the ocean.