The Prussian ministry read the Young Hegelians correctly. Hegel had taught a generation that history was the unfolding of spirit, that the state embodied reason, and that philosophy's task was to comprehend what already was; his radical students turned that machinery against the Gospels and the church, and in the Prussia of the early 1840s attacking religion was the boldest thing a young intellectual could do. The universities were being closed to exactly that circle, and a doctorate on Democritus and Epicurus, taken at Jena in April 1841, bought its author no chair.
So Marx became a newspaperman in Cologne, and the newspaper is where the philosophy broke. He joined the editorial board of the Rheinische Zeitung on 15 October 1842 and spent that autumn covering the Rhenish assembly's debates on the law against the theft of wood — peasants who had gathered fallen branches from the forests for generations, now prosecuted as criminals because the landowners wanted the deadwood. In January he wrote on the ruin of the Moselle winegrowers. Sixteen years later he dated his whole turn to economics from those two assignments. Hegel had promised a state that stood above private interest and reconciled it; he had just watched a legislature spend weeks converting one class's property claim into law.
The central claim follows from that, and everything else rests on it: the way people organise the production of their own means of life is what sets the shape of their politics, their law and their ideas, rather than the reverse. It is a theory about why people believe what they believe.
Prussia had him expelled from Paris in 1845; he gave up his Prussian citizenship the same year and never held another. Ordered out of Germany again on 16 May 1849, he reached London that August, stateless, in his thirties, with the rest of his life still to run. He filed for the New-York Daily Tribune from 1852 to 1862. His actual income was Engels, drawing on the Manchester cotton firm his father owned — the factory system paying for the analysis of the factory system.
The analysis arrived in 1867, in Capital, which argues that profit is not a reward for risk or shrewdness but the value of the working day beyond what the worker's wage covers, extracted lawfully, without breach of contract or theft: the system does not malfunction when it exploits, it functions. Volume one was the only one he finished. Engels assembled volumes two and three from the manuscripts, in 1885 and 1894, after his death in March 1883.
He has kept being rediscovered since. The argument is still open in the places that matter: whether the labour theory of value survives the problem of converting values into prices, whether Marx thought capitalism unjust or only doomed, whether his late work points toward growth or away from it. The 1844 manuscripts on alienated labour — work that confronts its maker as an alien thing — sat unpublished until 1932, and handed the twentieth century a second Marx it had not known about.