Why was the Equity of Redemption = property worth — still owing mortgage debt? And not only the latter?
<p>Source: <a href="http://emond.ca/introduction-to-law-in-canada.html" rel="nofollow noreferrer"><em>Introduction to Law in Canada</em></a> (2014). pp. 288 Bottom - 289 Top.</p>

<blockquote>
  <p>  In simplified terms, a <strong>mortgage</strong> is a kind of charge against land that secures a debt owed 
  by the landowner. The modern concept of a mortgage differs from the traditional concept. </p>
  
  <p>Traditionally, a mortgage involved transferring the landowner's title to the land to the lend- 
  er. The lender would hold this title as security against the loan, with a promise to transfer 
  title back to the owner once the latter had repaid the mortgage loan in full. If the owner/borrower (the mortgagor) missed a payment or otherwise went into default, the lender (the 
  mortgagee, often a bank) was entitled to keep the land unconditionally. However, in equity, the mortgagor was given a period of time to come up with the balance—in other words, 
  a redemption period (see the discussion of the Court of Chancery, in Chapter 2). The owner's right to redeem his property came to be known as the mortgagor's "equity of redemption"; <code>it was valued at the worth of the property minus the amount of the mortgage debt still 
  owing.</code> Hence we now refer to a property owner's "equity" in the property, which refers to 
  the net market value of his unencumbered interest in the property. </p>
</blockquote>

<p>Why wasn't the Equity of Redemption instead only <code>the amount of the mortgage debt still 
owing</code>? This is what the mortgagor must pay, NOT the sentence coloured in gray.</p>

<p>The <strong>equity of redemption</strong> is the right to pay off the mortgage balance. </p>

<p>The <strong>value of the equity of redemption</strong> to the person obligated on the mortgage, a.k.a. the <strong>equity</strong> in the property, is the value of the property less the amount of the mortgage.</p>

mortgage