▁wrote ▁at ▁length ▁on ▁issues ▁that ▁would ▁later ▁concern ▁econom ists , ▁such ▁as ▁tax ation , ▁Vel ocity ▁of ▁money ▁and ▁national ▁income , ▁but ▁while ▁his ▁analysis ▁was ▁numerical , ▁he ▁rejected ▁abstract ▁mathematical ▁method ology . ▁ ▁Pet ty ' s ▁use ▁of ▁detailed ▁numerical ▁data ▁( al ong ▁with ▁John ▁Gra unt ) ▁would ▁influence ▁statist icians ▁and ▁econom ists ▁for ▁some ▁time , ▁even ▁though ▁Pet ty ' s ▁works ▁were ▁largely ▁ignored ▁by ▁English ▁sch ol ars . ▁ ▁The ▁mathemat ization ▁of ▁econom ics ▁began ▁in ▁earnest ▁in ▁the ▁ 1 9 th ▁century . ▁ ▁Most ▁of ▁the ▁economic ▁analysis ▁of ▁the ▁time ▁was ▁what ▁would ▁later ▁be ▁called ▁classical ▁econom ics . ▁ ▁Sub ject s ▁were ▁discussed ▁and ▁disp ensed ▁with ▁through ▁algebraic ▁means , ▁but ▁calculus ▁was ▁not ▁used . ▁ ▁More ▁important ly , ▁until ▁Johann ▁Heinrich ▁von ▁Th ün en ' s ▁The ▁Is ol ated ▁State ▁in ▁ 1 8 2 6 , ▁econom ists ▁did ▁not ▁develop ▁explicit ▁and ▁abstract ▁models ▁for ▁behavior ▁in ▁order ▁to ▁apply ▁the ▁tools ▁of ▁mathematics . ▁ ▁Th ün en ' s ▁model ▁of ▁far ml and ▁use ▁represents ▁the ▁first ▁example ▁of ▁marg inal ▁analysis . ▁ ▁Th ün en ' s ▁work ▁was ▁largely ▁theoretical , ▁but ▁he ▁also ▁m ined ▁empir ical ▁data ▁in ▁order ▁to ▁attempt ▁to ▁support ▁his ▁general izations . ▁ ▁In ▁comparison ▁to ▁his ▁contempor aries , ▁Th ün en ▁built ▁economic ▁models ▁and ▁tools