Among such writers no one has upheld the testimony of these facts more strongly than Sismondi.[370] All his interest in political economy, so far as theory was concerned, was summed up in the explanation of crises, so far as practice, in the amelioration of the condition of the workers. No one has sought the explanation or striven for the remedy with greater sincerity. He is thus the chief of a line of economists whose works never ceased to exercise influence throughout the whole of the nineteenth century, and who, without being socialists on the one hand or totally blind to the vices of _laissez-faire_ on the other, sought that happy mean which permits of the correction of the abuses of liberty while retaining the principle. The first to give sentiment a prominent place in his theory, his work aroused considerable enthusiasm at the time, but was subjected to much criticism at a later period. I: THE AIM AND METHOD OF POLITICAL ECONOMY Sismondi began his career as an ardent supporter of economic Liberalism. In 1803, the year that witnessed the production of Say’s treatise, he published an exposition of the ideas of Adam Smith in a book entitled _La Richesse commerciale_, a volume which achieved a certain measure of success. During the following years he devoted himself to work exclusively historical, literary, or political, and he only returned to the study of political economy in 1818. “At this period,” he writes, “I was keenly interested in the commercial crises which Europe had experienced during the past years, and in the cruel sufferings of the factory hands, which I myself had witnessed in Italy, Switzerland, and France; and which, according to public reports, were at least equally bad in England, Belgium, and Germany.”[371] It was at this moment that he was asked to write an article on political economy for the _Edinburgh Encyclopædia_. Upon a re-examination of his ideas in the light of these new facts he found to his surprise that his conclusions differed entirely from those of Adam Smith. In 1819 he travelled in England, “that wonderful country, which seems to have undergone a great experience in order to teach the rest of the world.”[372] This seemed to confirm his first impressions. He took the article which he had contributed to the _Encyclopædia_ and developed it. From this work sprang the treatise which appeared in 1819 under the significant title of _Nouveaux Principes d’Économie politique_ and made him celebrated as an economist. His path was already clear. His want of agreement with the predominant school in France and England was further emphasised by the appearance of his studies in economics,[373] in which he illustrates and confirms the ideas already expounded in the _Nouveaux Principes_ by means of a great number of descriptive and historical studies bearing more especially upon the condition of the agriculturists in England, Scotland, Ireland, and Italy.