There are two frequencies of Divine revelation in this world: constant and occasional. The constant is known as nature, the occasional as miracles.

The Askmoses Answer: 

The Talmud¹ relates the story of Rabbi Chaninah Ben Dosa, whose daughter once accidentally put vinegar instead of oil in the Shabbat lamp. He said to her: "Why are you sad? What difference does it make? He Who told oil to burn can tell vinegar to burn." The vinegar burned all Shabbat until they lit the Havdalah light from it after Shabbat. 

Common knowledge defines nature as a self propelled system of cause and effect, and a miracle as a supernatural occurrence. The believer might add that the self propelled system was created by G-d at the time of creation, and the miracle is G-d's intervention and overriding of that system.

Oil burns naturally. Vinegar does not. The miracle is that G-d made vinegar burn.

The Jewish view is quite different: 

In truth nature is just as awesome as a miracle, and a miracle is just as "natural" as nature. Both are the fulfillment of G-d's will at any given moment. It is merely the frequency of nature that makes it lose its miraculous effect, and it is only the infrequency of the miracle that suddenly reminds us of G-d's involvement in our life.

It is merely the frequency of nature that makes it lose its miraculous effect, and it is only the infrequency of the miracle that suddenly reminds us of G-d's involvement in our life.

Seen in this light, miracles aren't as much as an occurrence as they are an observance. In other words miracles are happening all the time, the question is only if we are observing them as such. Some times that observance is superimposed, and some times we must make an effort to see it. But ultimately we will perceive it only if we so desire. As the Talmud says, the skeptic will explain the splitting of the sea as a natural event, and the believer will explain the growth of wheat as a miracle.

Truth be told, just as G-d makes seas flow He can make them split, and just as He makes seeds fertile, He can make them sterile. So what separates the natural from the miracle? That which separates the skeptic from the believer: Perception. The skeptic attributes (even) the supernatural to a self governed system, whereas the believer attributes (even) the natural to a divinely governed law.

Thus the Hebrew word for Nature is Teva, which also means "sunk". In nature G-d's involvement is submerged and unnoticed. The Hebrew word for Miracle is Neis. Neis also means "sign".² A miracle is an occasional reminder that G-d's will drives nature. Constantly.

During the infancy of our existence miracles - uncommon G-dly revelations - were more blatant and occurred more often. At that time we were spiritually and intellectually immature, and needed more reminders of G-d's presence. But with time we matured and G-d lessened the superimposition of His presence; because He believes we can now see more miracles in the less noticeable.

Ultimately we will learn to recognize G-d as the driving force behind everything that occurs. We will view the consistency of nature as a prolonged miracle, and miracles will be the natural order.