This brief but fascinating book offers us an elaborate method of divining with a regular deck of cards. The technique is complicated and takes some time to perfect, but the results can be intriguing. I have tried the technique a few times and always received a clear and accurate response.
But before you plunge right in, here are a few pointers about the technique which the text does not make clear. First, remove the jokers from your deck before you start your reading--Antrobus only wants you to use the basic 52 cards. Then when you draw a card, leave it face up on the table (Antrobus is not clear about this). Finally (and this is just my opinion), you need a very definite question in mind before you set to work; just wondering what the cards might tell you about your life doesn't succeed very well, not with this method nor with Tarot.
Antrobus was also, alas, of the opinion that it was his duty to give his reader the "meaning" of the cards, and (surprise!) most of this book is taken up with with tiresome what-the-cards-mean definitions. Well, I can't say it too many times: what the cards (or the tea leaves or the runes) actually "mean" to one human being won't necessarily hold true for another. So you can follow his card definitions or not as you please.
One thing about his definitions, however, I did find intriguing: The Square of Sevens contains the earliest mention I have discovered about the meaning of the card suits. While I am never impressed with all the tortuous knots various authors tie themselves into when they attempt to define what-the-cards-mean, it is always valuable to learn how people define the four suits. One reason why card divination actually works is that the structure of the cards is based on the energies of the four classical elements. These energies are constantly manifesting in both our lives and in the world around us, and the cards can help us to see their patterns.
Antrobus describes the suits (or the energies of water, earth, fire and air) as follows:
Hearts: "the Suit of the Affections, Passions, Fancies and Feelings".
Diamonds: "Condition in Life, Society, Wealth, Position and the Fine Arts; and contains many Comfortable Cards".
Clubs: "the Judgment, the Intellect, the Will, and the Affairs of a Man's Brains, and what he doeth of his own Mastery and Genius".
Spades: "ever the suit of doubtful or worse Prognosticks; of the Events that arbitrarily fall to Man's Lot, those things which hardly can any Prescience or Plans or Conditions of our own making amend. Thence is it that in especiall comes a serious, nay even a gloomy appearance to the Parallelogram".
These nearly three-hundred-year-old words are as good a definition of the suit meanings as I have ever come across, and they apply equally well to the four Tarot suits of cups, pentacles, wands and swords. (Although let's face it--our author was perhaps a bit too hard on the energies of spades/swords.)
My own experience of using Antrobus' system is that what matters is not necessarily what the cards or the suits "mean", but whether you end up with mostly red or black cards at the end. This alone can give you a yes or no answer to your question. Antrobus seems to understand this when he states: "For a Red Aspect is kindly. A Black Aspect contains many less favorable cards, especially if they be Spades." After you've created your Master Column, if you've got mostly red cards showing, the answer to your question is most likely favorable; if most of your cards are black, you're seeing something negative.
One final note: at one point Antrobus uses the word tavola, which is simply the Italian word for table.
Read The Square of Sevens here