Jupiter is a medium-slow planet, as it remains in a constellation for ca. 12 months. It rules Sagittarius and from an astrological point of view, its energy is masculine.
It is the biggest planet of our Solar System and through its size Jupiter was anciently given a meaning of expansion, both on a matter level and on a psychological level.
Nowadays it has been sensed that Jupiter represents the regenerating principle of Life, of a single cell, which everything stems from. It takes the Spirit of the Sun spreading it all around, in each level of Existence, to bring the messagge carried by that Life vibration in the whole Universe. This is the reason why it embodies the principle of expansion.
It represents the Higher Mind, processing the information received from Mercury (human mind). Jupiter helps us to insert higher concepts in our life.
It represents expansion, according to its position in our natal chart.
In the First House, it expands our body, giving us a rounded physical form.
In the Second House, it expands our wealth, in terms of money or self-esteem.
In the Third House, it expands our relation ability, making it very easy for us to get acquainted with whosoever.
In the Fourth House, it indicates we are probably living in a big house or stem from a very numerous family.
In the Fifth House, it gives us the tendency of falling in love every two steps.
In the Sixth House it expands our sense of duty or health conditions, which will be basically very good.
In the Seventh House, our marriage is our richness, in every sense.
In the Eighth House, our social position will be high.
In the Ninth House, we are going to find ourselves in the position of a Master, sooner or later.
In the Tenth House, our professional career is everything to us.
In the Eleventh House, we are surrounded by myriads of friends, from every level of our life.
In the Twelfth House Jupiter expands our consciousness Beyond our physical limitations.
These are general indications. Jupiter should be observed in its resonance to the other planets, and consider the Zodiac sign it is in.
Talkin about Zodiac, in Fire signs (Aries, Leo and Sagittarius) Jupiter gives the native a firm character and determination.
In Air signs (Gemini, Libra and Aquarius) the native possesses great communication skills.
In Earth signs (Taurus, Virgo and Capricorn) Jupiter gives great self-consciousness.
In Water signs (Cancer, Scorpio and Pisces) the emotional world will be at its utmost expression in our life.
Being a medium-slow planet, as I wrote before, its action goes a little beyond normal perceptions and through its eyes we can look at life in a more detachted way, feeling ourselves not so involved in human pain and emotional turmoils. We can then perceive God's supreme force, which can stream through us, giving us the wonderful chance to get to the top in the House Jupiter is.
If Jupiter is badly aspected, the subject is going to feel stressed to get to the point. In this case, he/she will have to work on a deep level to discover his/her natural strength and on the other side, the real dark side. It is necessary to love it, in order to embrace and integrate it, making it our determination to get to the top.
Jupiter represents the miracle aspect in our life, it represents what life can transform itself into, if we allow the Universe to expand inside of ourselves. In this case we can get in touch with all the hidden treasures lying within. Saying YES is all we need to do. Jupiter enables us to break on through to the Love awaiting for us in the form of a new job, a new love affair, etc., according to what we need.
Jupiter is also Faith (it is the ancient ruler of Pisces, before the discovery of Neptune, and Pisces have to do with mysticism). It is the Faith necessary to operate a miracle. Believe and you will get what you need. Believe, stick to what your Heart desires and you will see.
Another hint about this side of Jupiter's nature is to be discovered in its symbol:
This symbol is the transformation of number 4 - the number of Reality, Responsability, Substance. Jupiter is the substance spread by expansion of love in our life.