create implication 1621 (2) -> 17th_century (44)
change category 1621 (2) -> meta
create implication 1779 (1) -> 18th_century (61)
change category 1779 (1) -> meta
create implication 12th_century_bc (2) -> ancient_art (1636)
create implication 13th_century_bc (1) -> ancient_art (1636)