"I have often wished that I had lived in an age when philosophy was more free and less tied to the authority of the ancients."

"I have often observed that those who are most fond of disputing, are generally the least desirous of being convinced."

"The book of nature is a fine and large piece of clock-work."

"I have often thought that the greatest obstacle to the progress of knowledge is the obstinacy of men in adhering to their old opinions."

"I have often found that a single experiment can overturn a thousand speculations."