The passion of avarice is the desire for wealth.
It is the love of money.
What’s wrong with that?
Judas betrayed Christ for money.
If the passion of fornication turns people into instruments of our pleasure, the passion of avarice turns them into instruments of our wealth. In fornication, instead of having a relationship of love with the other person, we have an instrumental relationship of sexual exploitation. We use the other person sexually.
In avarice, instead of loving the other person, we use him or her economically. We exploit him or her, the image of God, for our own wealth. We start to have a calculating attitude towards our friends and relatives. With dollar signs in front of our eyes, we start to look at what we can get out of others.
St James in his epistle in the Bible points out that avarice is the cause of wars among men.
In the case where one nation exploits another, the masters often exploit the servants in both ways: both economically and sexually. This is an example of how one passion (avarice) when it has reached its full flower can bring on another passion (fornication). Avarice in full flower also brings on pride.
We once met someone completely free from avarice. He was as free as a bird. He had a great charity, a great spiritual love for all men. God gave him everything he needed, sometimes by outright miracle. That is why avarice is idolatry: we no longer trust God; we think that the words of the Bible about God’s providence are just words, nothing more; we put our confidence not in God but in stocks and bonds.