Historically, care for foundlings tended to develop more slowly or with greater variation from country to country than, for example, care for orphans. The reason for this discrepancy was the perception that children abandoned by their parents carried with them a burden of immorality. Their parents tended to be unmarried and poor. Alleviating the burden of unwanted pregnancies was often seen as encouraging infidelity and prostitution. Thomas Malthus, for example, the noted English demographer and economist, made, in his "The Principles of Population" (vol. i. p. 434), a violent attack on foundling hospitals. He argued that they discouraged marriage and therefore population, and that even the best management would be unable to prevent a high mortality. He wrote: "An occasional child murder from false shame is saved at a very high price if it can be done only by the sacrifice of some of the best and most useful feelings of the human heart in a great part of the nation".