base  mod  botch
fighter       -20   1/1  15
paladin       -5    3/2  25
ranger        -15   3/2  25
thief         0     2/1  20
assassin      -15   3/2  20
wizard        30    3/1  50
priest        30    5/2  40
bard          5     2/1  30
monk          -10   3/2  20
healer        10    7/3  35
weaponsmith   -10   3/2  20
archer        -20   1/1  15
merchant      -20   2/2  20
farmer        -10   1/1  10
mindcrafter   -40   1/4  -10
barbarian     -30   1/8  -20
druid         20    2/1  30
necromancer   20    3/1  40
elementalist  20    3/1  50
beastfighter  10    1/1  20

chance to learn spell = base + mod*Learning + [other modifiers]
botch modifies chances of bad stuff occurring

pulled from ADOM 1.1.1 for Mac OS X