Code:
<blockquote class="calibre8">Come hither, my lads, with your tankards of ale,<br class="calibre4"/>
Code:
<blockquote class="calibre8">“—the vastness, profundity, and unsearchableness of His works, <em class="calibre6">which have a depth in them greater than the well of Democritus.</em>”</blockquote>
What is even funnier is that when I ran those code snippets through epubcheck using epub3 (I did add the closing blockquote to the first snippet), there were no errors.
When I repeated running epubcheck using epub2, I needed to add a block tag inside the blockquotes which oddly is what first error message posted for both was complaining about. I tested with <div> and <p>, any of the others would likely work.
Code:
<blockquote class="calibre8"><p>Come hither, my lads, with your tankards of ale,<br class="calibre4"/></p></blockquote>
<blockquote class="calibre8"><p>“—the vastness, profundity, and unsearchableness of His works, <em class="calibre6">which have a depth in them greater than the well of Democritus.</em>”</p></blockquote>
Perhaps either more practice or an online CSS course and a review of the ePub specifications might be in order.