In Egypt, medicine was organized almost 3000 years before our era. The Greeks were influenced by the Egyptians, e.g., the Greek Hippocrates (c. 460–c. 370 BC) studied in the library in Egypt. Medicine was developed in China and India more or less at the same time that it grew in Greece. These two civilizations kept many early practices to this day. Medical instrumentation was created in antiquity and refined over the centuries, allowing the measurement of blood pressure and body temperature and registering the electrical activity of the heart and brain. Records of the use of magnets in medicine are very old: e.g., in India, a magnet helped to extract an arrow tip in 600 BC. Today, several techniques use the magnetic moments of nuclei in magnetic resonance imagingmagnetic resonance imaging (MRI) (MRI) and functional MRI (fMRI), employed to obtain images of the organs. Using the magnetic properties of the hemoglobin or magnetic fields generated by active regions of the brain, neural activity can be mapped. Other applications of magnets include guiding instruments such as catheters and using microscopic magnetic particles in diagnoses and therapy. Finally, in the eighteenth century, Friedrich Anton Mesmer (1734–1815) created a treatment using magnets that was denounced as non-scientific.