The Judges of all of the said Courts shall be citizens of the State of Maryland, and qualified voters under this Constitution, and shall have resided therein not less than five years, and not less than six months next preceding their election, or appointment, as the case may be, in the city, county, district, judicial circuit, intermediate appellate judicial circuit or appellate judicial circuit for which they may be, respectively, elected or appointed. They shall be not less than thirty years of age at the time of their election or appointment, and shall be selected from those who have been admitted to practice Law in this State, and who are most distinguished for integrity, wisdom and sound legal knowledge.