The power of taxation shall never be surrendered, suspended or contracted away. Taxes shall be uniform upon the same class of subjects and shall be levied and collected for public purposes, but public burying grounds, public school houses, public hospitals, academies, colleges, universities, all seminaries of learning, all churches, church property, houses of worship, institutions of purely public charity, and public property used exclusively for any public purpose, shall be exempt from taxation except as provided in this section. There may be exempted from taxation personal property not exceeding in value $200 for each household, individual or head of a family, and household goods and farm machinery as the legislature determines. The legislature may authorize municipal corporations to levy and collect assessments for local improvements upon property benefited thereby without regard to cash valuation. The legislature by law may define or limit the property exempt under this section other than churches, houses of worship, and property solely used for educational purposes by academies, colleges, universities and seminaries of learning.