Both depression and Melancholy can be traced back in a natal chart.
Saturn is the main significator of Depression and Melancholy, this due to it’s restrictive and cold nature.
It’s malefic power will be more influential in a night chart due to it’s sect.
The strength of the Moon plays an important role in determining the tendency for depression in a natal chart :
The Moon is damaged either by sign placement (Scorpio, Capricorn)
The Moon is damaged by a hard aspect

If the Moon is already challenged in the natal chart and one receives a difficult transit from Pluto or Saturn,
It can bring a period of (heightened) depression.
Depression can be triggered through progressions.
Most vulnerable : Sun – Moon – Mercury – Ascendant – Lunar nodes

The synastry of a relationship needs to be considered too in case the native has a natal inclination for depression.
That means if the Moon of person A is challenged natally, and receives hard aspects from Saturn, Pluto from person B, the relationship probably only contributes to a more depressive flavor within the union. One may feel triggered by their partner, whether it’s conscious or unconscious.

Depression in the natal chart

• Saturn in hard aspect to Sun or Moon
• Saturn in hard aspect to Mercury
• Pluto in hard aspect to Sun or Moon
• Pluto in hard aspect to Mercury
• Saturn / Pluto in hard aspect to the lunar nodes
• Saturn / Pluto in hard aspect to the ASC
• Moon conjunct Southnode
• Personal planets in Scorpio or Capricorn
• 8th house emphasis

Degrees of depression

29° Aries (isolation)
2° Taurus (pessimism, despair)
12° Cancer
18° Gemini (sorrow)
12° Virgo (strife, sorrow)
0° Libra (bitterness, sweetness in pain)
3° Libra (bitterness)
8° Libra
23-24° Scorpio (sorrow)
16° Sagittarius (isolation, abandonment)
28° Capricorn
2° Aquarius (sorrow)
17° Aquarius (bitterness, isolation)
23° Aquarius (sorrow)
28° Aquarius (sorrow)
18° Pisces
28° Pisces

Melancholy in the natal chart

• Moon in hard aspect with Sun, Saturn, Mars
• Moon in Capricorn, Scorpio
• Mercury in hard aspect with Saturn, Mars
• Mercury in Virgo, Pisces, Scorpio + hard aspect of Saturn / Mars
• Saturn in 1st or 4th house
• Saturn conjunct to an Angle
• Saturn in hard aspect to Jupiter or Northnode
• Capricorn, Aquarius rising or dominant chart

Degrees of Melancholy

1°  Taurus
26°  Gemini
9°  Cancer
11°  Cancer
16°  Cancer
11°  Virgo
23°  Virgo
29°  Virgo
1°  Libra
7°  Libra
12°  Libra
28°  Libra
1°  Scorpio
4°  Sagittarius
9°  Capricorn
11°  Capricorn
29°  Capricorn
17°  Aquarius
9°  Pisces
14°  Pisces

Degrees of hermit

14° Aries
5° Taurus
9° Libra
16-17° Scorpio

More info will be added later!