MARBLEHEAD-After nearly three months of word-wrangling, the Marblehead schools have a vision statement.The School Committee has approved the wording for the third and final time: “To develop in our students a Critical Spirit, the mastery of disciplines, creativity, inquisitiveness, a truth-seeking disposition and keenness of mind.”Committee members found themselves torn between the creative thinking the schools aspire to and the more conventional academic pursuits, however.A month ago the committee approved the phrase “a disciplined mind” in place of “the mastery of disciplines,” but they wound up substituting the words “mastery of disciplines,” which refers to academic excellence instead. One may imply the other, but the committee wanted to be specific.Superintendent of Schools Paul Dulac noted that “Kids (in our schools) will develop a mastery of disciplines. That?s our bread and butter.”As Dulac said in a one-page discussion of the statement, “A student first develops a strong habit in the ways of a given discipline (English, math, science, history, etc.) through persistent practice and feedback from a master (teacher) in that discipline.”After achieving mastery, the student becomes aware of the discipline?s limitations “and is willing to consider other approaches.”Committee Chairman Amy Drinker and new committee member Richard Nohelty, a financial planner, researched corporate mission statements and came up with a variety of approaches, which they shared with the committee in a two-page report during the summer.They even quoted Marblehead?s 2006 superintendent search brochure, in which the search committee predicted, “We will forge a partnership between our community and our schools that demands the highest standards of personal and social responsibility, a rigorous education that challenges all students, and an innovative curriculum that fosters critical thinking, creativity and self-discipline.”