Of course we all know that God is “all knowing.” He knows everything that we do, think, and say even before we do it. He sees all things at all places and all times. However, is the same also true for the Blessed Mother and the Saints? Of course we can pray to them, but do they know what we want before we ask them? Do they see all things at all places and all times? Or is God the only one who is all knowing?
In my opinion God is the only one who is “all knowing.” He alone has a comprehensive knowledge of all things. He alone knows what will happen on earth before they actually happen.
The saints and the blessed in Heaven, including the Blessed Mother, enjoy what is known as the
beatific vision, where they see God “face to face.” In seeing God, they see all things in Him as well, though not in equal measure, but in proportion to the greatness of their sanctity. Therefore, in my opinion, the saints in heaven have a knowledge of what happens here on earth, and the Blessed Mother could hear all the petitions of her children. I could not say the same about the souls in purgatory. Since these souls have not received the beatific vision yet, I don’t think that they really have a knowledge about what is happening on earth, unless it is revealed to them by God, or by one of the angels or the saints.
Although the saints know all things through their vision of the Divine Essence, it does not mean that they know everything as God knows them. For example, only God knows Himself perfectly, while the saints know Him only in a limited way - limited by their finite grace and their finite being. In addition, God knows the future because He lives in a different duration, - the NOW of eternity, - where He sees the past, the present and the future. The saints, however, are living in time - a time that will have no end, - but in the “now” of time they only see the present, not the past nor the future. If they ever need to know anything about the future, I suppose, they could always ask God to reveal the matter to them.