Ricardo was elected to the British parliament in 1819 as an independent representative of a borough in Ireland, Portarlington, which he served till his death in 1823.
David Ricardo, lived in the times just at the beginning of the Industrial revolution and this is what perhaps influences his thinking on 'Machinery' (discussed below). Ricardo took a keen interest in the study of economics and formulated the 'Classical' system of political economy. His interest in economics was sparked by a chance reading of Adam Smith's 'The Wealth of Nations' while on vacation in 1799, in which Adam Smith focuses most of his attention on the problem of economic growth and his belief that an evolving capitalist system could benefit society as a whole. According to Smith's analysis the economy possesses unlimited upward potential.
Ricardo's first written comments on economics appear to be two essays written in 1810 and 1811 (The High Price of Bullion, a Proof of the Depreciation of Bank Notes) articulating his position in favour of the 'Bullionist' position. He argued in favour of a metallic currency, giving a fresh stimulus to the controversy about the policy of the Bank of England. This has since become known as the classical approach to the theory of money, which argued for the resumption of the convertibility of paper money into gold. The Bullion Committee appointed by the House of Commons in 1819 confirmed Ricardo's views and recommended the repeal of the Bank Restriction Act.
Ricardo was a firm believer in Say's Law that states that there can be no demand without supply and that recession does not occur because of failure in demand or lack of money. In these tracts Ricardo also suggested the impossibility of a 'general glut', or an excess supply of all goods in an economy as proposed by Thomas Robert Malthus. This provoked a debate with Malthus that culminated in Ricardo writing a series of notes on Mathus's 1820 'principles'. These notes were published posthumously as Notes on Malthus.
In 1815 he published his first complete work 'Essay on the Influence of a Low Price of Corn on the Profits of Stock' where he introduced the differential theory of rent and the "law of diminishing returns" to land cultivation. He argued that raising the duties on imported grain had the effect of increasing the price of corn and hence increasing the incomes of landowners and the aristocracy at the expense of the working classes and the rising industrial class.
In Essay Ricardo formulated his theory of distribution in a one-commodity ("corn") economy. With wages at their "natural" level, Ricardo argued that rate of profit and rents were determined residually in the agricultural sector. He then used the concept of arbitrage to claim that the agricultural profit and wage rates would be equal to the counterparts in industrial sectors. With this theory, he could show that a rise in wages did not lead to higher prices, but merely lowered profits.
Ricardo took economics to an unprecedented degree of theoretical sophistication by formalising the 'Classical' system more clearly and consistently than anyone before had done and what became known as the "Classical" or"Ricardian" School (of thought).