(Calef, 2015) Descartes in his thought experiments could conceive the possibility of dividing his body, but he could not imagine the division of his mind. For example, you might take the case of someone with an illness that has ravaged their body rendering them unable to physically interact with the world, but who still has a fully agile mind that is able to interact with the world around them through thoughts and ideas, or that of a dementia patient whose mind is ravaged by the disease but still physically functions normally. This lends credence to the thesis that the body and mind are not identical because if they were identical substances, the mind and body would show equal signs of disease