We have a remarkable evidence of domestic unhappiness annihilating the very faculty of genius itself, in the case of Dr. BROOK TAYLOR, the celebrated author of the "Linear Perspective." This great mathematician in early life distinguished himself as an inventor in science, and the most sanguine hopes of his future discoveries were raised both at home and abroad. Two unexpected events in domestic life extinguished his inventive faculties. After the loss of two wives, whom he regarded with no common affection, he became unfitted for profound studies; he carried his own personal despair into his favourite objects of pursuit, and abandoned them. The inventor of the most original work suffered the last fifteen years of his life to drop away, without hope, and without exertion; nor is this a solitary instance, where a man of genius, deprived of the idolised partner of his existence, has no longer been able to find an object in his studies, and where even fame itself has ceased to interest. The reason which ROUSSEAU alleges for the cynical spleen which so frequently breathes forth in his works, shows how the domestic character of the man of genius leaves itself in his productions. After describing the infelicity of his domestic affairs, occasioned by the mother of Theresa, and Theresa herself, both women of the lowest class and the worst dispositions, he adds, on this wretched marriage, "These unexpected disagreeable events, in a state of my own choice, plunged me into literature, to give a new direction and diversion to my mind; and in all my first works I scattered that bilious humour which had occasioned this very occupation." Our author's character in his works was the very opposite to the one in which he appeared to these low people. Feeling his degradation among them, for they treated his simplicity as utter silliness, his personal timidity assumed a tone of boldness and originality in his writings, while a strong personal sense of shame heightened his causticity, and he delighted to contemn that urbanity in which he had never shared, and which he knew not how to practise. His miserable subservience to these people was the real cause of his oppressed spirit calling out for some undefined freedom in society; and thus the real Rousseau, with all his disordered feelings, only appeared in his writings. The secrets of his heart were confided to his pen.