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phantoms; the authority of great names, and the attraction of beautiful theories nicely accommodated and smoothly glossed over, give these emanations of thought the semblance of truth; and those who will not receive them are regarded as far behind in that which constitutes mental vigour and attainment. The vague notions of Galen had immense power and held the minds of men in bondage for nearly 1,200 years; and, it was only when direct observations were made and dissections were carefully studied by Yesalius and Servetus, that those shackles upon thought were unloosed. Galen regarded one ventricle of the heart as connected with nutrition and nourishment; the other, the left, had to do with vital spirit; he believed, that the blood sent to the lung was especially for the nourishment of the lung itself, though he was quite ignorant of the circulation of the blood through the lungs. Vague notions of transfusions and interchange of blood and air between the arteries and veins were held, but nothing like the true
