There are 6 "f"s in this passage. If you only counted 3, you're not alone. Most people fail to count the "f's" in the word of. Why? When looking for "f's" your brain is actually scanning for the sound of the letter "f" – which usually makes the /f/ sound, like in fox. In the word of, though, "f" makes the /v/ sound. As a result, the brain overlooks the word of as it scans for the sound of /f/.
Cheers
Rick R.