By NUMBER@1 , when he was diagnosed as having prostate cancer , he had written most of the material that would be published after his death as PERSON@1 -LRB- Philosophical Investigations -RRB- .

When in NUMBER@1 one found out that he had cancer , he had written most of the material that would be published after his death as PERSON@1 -LRB- Philosophical Investigations -RRB- , which might be his most important work .
