Resolved: For almost a month, the lights in my house have been dimming and flickering. Based on most of the replies to my original post, I assumed the problem was either with our circuit-breaker(s) or with the wiring/fixtures in my house so I was going to call an electrician today.
However, last week, I reported the problem to my city's utility department.
Yesterday morning, a city utility worker came out and checked my circuit panel (it was OK) and he determined that the problem was with faulty connections in both the city's transformer (at the street) and the meter pedestal so he called in a team of city utility workers. About noon, 7 utililty workers in 5 trucks arrived and four hours later, my dimming/flickering lights problem had been resolved at NO COST to me. Now, I can see clearly again.
If I had called an electrician first, it would have cost me $$$$$$ and he would NOT been able to fix the dimming/flickering lights problem because it was caused by the faulty connection in the city's equipment.