Bloch brought a humanistic dimension to Marxist philosophy, embracing spiritual and cultural needs, and influenced liberation theology. He met Lukács at his teacher Simmel’s — an intimate friendship and intense philosophical partnership ensued. Jaspers was a fellow-member of a group of friends who met weekly at Weber’s (who wore his reserve officer’s uniform). Kracauer was a colleague on a Berlin journal, and corresponded for 40 years. Adorno, Weill, Brecht and Herzfelde were also friends, the last two colleagues in U.S. exile. Bloch and Benjamin took drugs together, assiduously annotating their experiences.
Hutcheson was responsible for Glasgow’s role in the Scottish Enlightenment, influencing both Hume and Smith, its greatest figures. Lesser known than he might be (because while teaching in English, he published in Latin), his textbooks were influential in Scottish and U.S. universities through the 18th C. Smith and Reid were students of his (he has been described as his students’ banker, guardian and friend); Smith fondly called him “never to be forgotten”. Hume cut his teeth in philosophical jousting with Hutcheson, and although Hutcheson tried to hinder Hume’s career, they corresponded until Hutcheson’s death.
Stewart, a brilliant teacher, was an influential member of Scottish Enlightenment circles. He was taught by Ferguson, who recommended he go to Glasgow to attend the common-sense philosopher Reid’s lectures. Reid became his mentor, and Stewart took over Ferguson’s position when his former teacher was sent to America. Among Stewart’s own students were Scott, Mill and Sydney Smith. He was influenced by Monboddo, friendly with Burns, Edgeworth and Playfair, and observed the beginning of the French Revolution with Jefferson. A member of Adam Smith’s Oyster Club, he wrote biographies of Smith and Reid.
Initially known more as a mathematician, Sulzer grappled at length with the formation of a unified aesthetic theory, which stimulated the ultimately more influential ideas of the likes of Kant (a correspondent) and Schiller. Bodmer taught him in Zürich. Maupertuis, Euler and C. P. E. Bach were among those befriended in Berlin, where Lambert became a colleague; others met in Prussian enlightenment circles included Mendelssohn and Lessing, who both criticised his ideas as somewhat outmoded. Burney visited him in Berlin, as did Lavater and Fuseli (more recent students of Bodmer’s); Klopstock was his companion on a journey back to Switzerland.
Condillac attempted a rigorous understanding of the relations between sensation and cognition. D’Alembert was a long-term (and fond) friend, Rousseau another. Rousseau, met as wayward tutor to Condillac’s brother’s children, introduced him to Diderot: both were regular dining companions (as was Buffon), and Diderot helped him find a publisher. Maupertuis, Beccaria, La Condamine and Voltaire were all correspondents. Montesquieu and Marivaux were met at the salon run by d’Alembert’s mother; despite his closeness to d’Alembert and Diderot, it’s thought Condamine wasn’t an Encyclopédiste.
Steffens brought a strong if highly individual scientific awareness to his philosophy, and was an important influence on Danish nationalism. He studied under the geologist Werner, but before that was a student in Jena, where he met the brothers Schlegel, Fichte, Novalis (who was stimulated by his zoological ideas) and Goethe (who failed to appreciate his work). He was a close disciple of one friend, Schelling, a colleague of another, Schleiermacher, and wrote an essay for a third, Runge. He knew the eccentric Ritter, influenced Ørsted (whom he admired) and Grundtvig, and changed Oehlenschläger’s life in a single meeting.
Bolzano’s pioneering ideas in mathematical logic were only properly appreciated after his death. He did mathematical research under Gerstner, but Austrian state censorship (Bolzano was banished from Prague and from academia for two decades) helped deprive him of contact with his intellectual peers; Abel, Lobachevsky and Gauss all knew of him, without having any direct contact. He was keen to meet Cauchy (their independently-conceived work had much in common), and seemingly did so, when Cauchy arrived for an unrewarding post in Prague. Dobrovský, a key player in Czech national culture, was a keen supporter.
Wollstonecraft (among the congregation at Price’s chapel), Godwin, Blake, Priestley, Franklin and Johnson were all members of the same radical-dissenting circle on the outskirts of London. Priestley took over Price’s ministry, and read his funeral oration — their often-oppositional views only seemed to strengthen their friendship. Price got some of his friend Bayes’ work on probability posthumously published – his own work was foundational for insurance and pensions business. Franklin corresponded with him about hot-air balloons and population-growth, and got him to advise Congress on finance; Condorcet, Turgot, Smith (who did not respect his abilities), and Hume (who visited), also all corresponded.
Oken’s Naturphilosophie is very much of its time. Agassiz, Schimper and Braun, student friends, went together to study in Munich under the congenial Oken, spending pleasant weekly discussion evenings at his house. Nägeli and Büchner were also students of his — Oken supervised Büchner’s thesis. Both Schelling and Döllinger had taught him, before eventually becoming his colleagues in Munich. Schelling also lent him money and advised him on how to approach the formidable Goethe, who had supported his Jena appointment but then been piqued at his claims for osteological primacy (decades later, Oken was still grumbling to his friend Owen about Goethe’s audacity).
Thoreau, not as reclusive as reputed, was friends (often close) with many authors of mid-19th-century classics. He worked for his neighbour and mentor Emerson as tutor, handyman and gardener. Hawthorne was a fireside companion, described his ugliness as honest and agreeable, and took him to dine with Longfellow. Whitman gave him a personal copy of ‘Leaves of Grass’. Thoreau told Louisa May Alcott how frogs were more confiding in the spring (she said that his beard would deflect amorous advances). He built a fancy summerhouse for her father, and sent Agassiz specimens from Walden Pond at age 12.