The horse was a beautiful creature. You could sense its power and strength.
You could sense the strength and power of the beautiful create that was the horse.
When looking at the horse, that beautiful creature, you could sense it's power and strength.
Explanation:
There are many ways to connect those two phrases that might use a preposition or some form of punctuation to do so. All of the answer above are valid examples of how to rewrite that sentence.
The main conflict in The Gift of the Magi is poverty. Because of their poverty, Jim and Delia have to make great personal sacrifices to buy the other a Christmas present.