Umkhathi
Umkhathi (noma isikhala) ngokwencazelo elula uyisilinganiso semingakontathu yomgamu ehlanganisa ubude, ububanzi, nokuphakama. Ngokomchazandalo wanamuhla umkhathi uyisilinganiso semingakomine esingenamkhawulo esibizwa ngokuthi umkhathinkathi, okusho ukuthi kujotshelelwa nesikhathi. Isicabango somkhathi sithatha njengesibaluleke kakhulu ekuqondeni kwethu umkhathilibe. Kodwa, ukungaboni ngaso linye phakathi kosonjulalwazi kuyaqhubeka neiba angavumelani ukuthi ingabe umkhathi ungumenzo, noma ubuhlobo phakathi kwemenzo, noma uyingxenye yohlaka lesicabango.
Ekhulwini leminyaka ye-19 nelama-20 abachazizibalo baqala ukuphenya izincazosimo okungezona ezika-Euclide, lapho okucatshangwa khona ukuthi umkhathi uyankumbela kunokuba yisicaba. Ngokomchachiso wokucakathana jikelele ka-Albert Einstein, umkhathi ongunge umnyondo uyanhlanhlatha encazelweni yomkhathi ka-Euclide. Imigcanso yokucakathana jikelele yafakazela ukuthi izincazosimo okungezona ezika-Euclide zinonongo olungcono lommumo womkhathi.