is wrong. Exponential growth, thankfully, can&#39;t go on forever. One thing that stops a virus from spreading is if others <em>already</em> have the virus:</p>

	<p><img src="pics/susceptibles.png" alt=""></p>

	<p>The more <span class="nowrap"><icon i></icon>s</span> there are, the faster <span class="nowrap"><icon s></icon>s</span> become <span class="nowrap"><icon i></icon>s,</span> <strong>but the fewer <span class="nowrap"><icon s></icon>s</span> there are, the <em>slower</em> <span class="nowrap"><ic