`` one of them things , yeah ... see , sometimes it just happens a little bit , and you get ghosts , because the life is not in the body any more but it has n't gone ... and you get less of it in the winter , because it sort of drains away , and it comes back in the spring ... and some things concentrate it ... '' modo the university gardener hummed a little tune as he wheeled the strange trolley into his private little area between the library and the high energy magic building , with a load of weeds bound for composthood .