That which is accepted as knowledge today is sometimes discarded tomorrow.

This 'famous' quote can be described as the embodiment of modern-day science. With the rapidly changing advances in technology in the twenty-first century, it is hard to state anything as an indisputable fact. Although this quote clearly falls under the category of 'natural sciences,' I think it also applies to areas such as ethics and history.
Although the definition of ethics remains the same, the situations applied to it change constantly. It was once acceptable to treat African Americans as if they were less than a person. Whether or not people in the 19th century considered slavery ethical, the public opinion and popular belief has greatly shifted since then.  This highlights the shift of knowledge (a justified true belief).  The belief that white people were superior was 'accepted' as knowledge, just as the modern-day belief that global warming exists as a major problem in the 21st century.  In a few years, advanced technology or just a shift in public opinion may convince people that it is not actually a great threat.
Another aspect of this topic that the quote leaves out is the ethics of sharing knowledge.  If someone is a genius, do they have the obligation to share their knowledge to the rest of the world, therefore changing some fundamental aspects of knowledge forever? Although the answer to this question is not black and white, it highlights how the shift in knowledge is also not black and white.  The 'answer' to a problem or the solution to a scientific method may be perfectly clear, but it may not be the right time to find it.