This painting is about the mental in a state of deterioration or decay which is here manifested in the physical as well. The bronze statue of a headless woman with an hourglass head symbolizes time's effect on our mental faculties specifically memory. One of the most amazing things about our body is that all cells regenerate EXCEPT for brain cells which is how it is possible to remember things from our earliest years (once the neuron pathways have developed enough—at around the age of 3 years old).
The broken bust of the man allows passing clouds to run through his now empty head. The seahorse represents the hippocampus (Greek for seahorse), which is an organ in the limbic system in the midbrain that regulates memory.