unknown to science
... that the stripes on tulips that caused tulip mania were probably caused by a virus, but this was unknown to science at the time?
... that the stripes on <a href="./Tulip" id="mwE2w" rel="mw:WikiLink" title="Tulip">tulips</a> <i id="mwE20">(examples pictured)</i> that caused <a href="./Tulip_mania" id="mwE24" rel="mw:WikiLink" title="Tulip mania">tulip mania</a> were probably caused by a <a href="./Virus" id="mwE28" rel="mw:WikiLink" title="Virus">virus</a>, but this was <b id="mwE3A"><a class="mw-redirect" href="./History_of_viruses" id="mwE3E" rel="mw:WikiLink" title="History of viruses">unknown to science</a></b> at the time?