Marten believed that an infectious micro-organism was the cause of tuberculosis, thus forecasting the existence of the tubercle bacillus 162 years before its actual discovery. Though Leeuwenhoek reported seeing bacteria in 1676 he did not believe that his "little animals" caused disease. Martin wrote that tuberculosis may be caused by "wonderfully minute living creatures" that could lead to the lesions symptomatic of the disease, thereby expressing the theory of contagium vivum or 'living contagion'. He went on to state that "it may be therefore very likely that by a habitual lying in the same bed with a consumptive patient, constantly eating and drinking with him, or by very frequently conversing so nearly as to draw in part of the breath he emits from the lungs, a consumption may be caught by a sound person...I imagine that slightly conversing with consumptive patients is seldom or never sufficient to catch the disease."