it is impossible in the modern world for a man of science to say with any honesty, my business is to

provide knowledge, and what use is made of the knowledge is not my responsibility. the knowledge that a man of science, or even a large body of men of science, can altogether prevent this but they can

diminish the magnitute of the evil.
여기서 this가 가리키는 것이 뭔지 모르겠어여..ㅠㅠ 그리고 the knowledge의 동사가 없는거같은데..ㅠㅠㅠ

can prevent가 동사라면 a man of science의 동사는 뭔가요..ㅠㅠ 답변해주시면 감사하겠어여.ㅠㅠ