Germán Bernácer, a Spanish economist of the early 20th century, proposed
in his 1925 book Interés del capital. El problema de sus orígenes
that the interest rate’s origin is external to the regular functioning
of the economic system. He attributed it to the income generated by
“income goods.” This study examines the plausibility of Bernácer’s
hypothesis using up-to-date data from the Spanish economy.