therefore, crowd into spheres of production which Modern Industry has only sporadically or incompletely got hold of. Here competition rages.... It always ends in the ruin of many small capitalists, whose capitals partly pass into the hands of their conquerors, partly vanish." Rate of accumulation In Marxian economics, the rate of accumulation is defined as (1) the value of the real net increase in the stock of capital in an accounting period, (2) the proportion of realized surplus-value or profit-income which is reinvested, rather than consumed. This rate can be expressed by means of various ratios between the original capital outlay, the realized turnover, surplus-value or profit and reinvestment's (see, e.g., the writings of the economist Michał Kalecki). Other things being equal, the greater the amount of profit-income that is disbursed as personal earnings and used for consumption purposes, the lower the savings rate and the lower the rate of accumulation is likely to be. However, earnings spent on consumption can also stimulate market demand and higher investment. This is the cause of endless controversies in economic theory about "how much to spend, and how much to save". In a boom period of capitalism, the growth of investments is cumulative, i.e. one investment leads to another, leading to a constantly expanding market, an expanding labor force, and an increase in the standard of living for the majority of the people. In a stagnating, decadent capitalism, the accumulation process is increasingly oriented towards investment on military and security forces, real estate, financial speculation, and luxury consumption. In that case, income from value-adding production will decline in favour of interest, rent and tax income, with as a corollary an increase in the level of permanent unemployment. As a rule, the larger the total sum of capital invested, the higher the return on investment will be. The more capital one owns, the more capital one can also borrow and reinvest at a higher rate of profit or interest. The inverse is also true, and this is one factor in the widening gap between the rich and the poor. Ernest Mandel emphasized that the rhythm of capital accumulation and growth depended critically on (1) the division of a society's social product between necessary product and surplus product, and (2) the division of the surplus product between investment and consumption. In turn, this allocation pattern reflected the outcome of competition among capitalists, competition between capitalists