According to Wikipedia, "an equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator." This is a good thing for this week is the Vernal Equinox that represents the official end of winter and start of spring.
Spring brings with it a new set of clothing challenges and opportunities, among them how to cope with days that can be both warm and chill. I like a spring sweater knitted from lighter weight yarn for that purpose on casual days. Cotton is commonly used for its lower cost but tends to stretch and much of it lasts only a couple of seasons. Linen works well for temperature control but has a slightly rustic finish. The prince of fabrics, cashmere, on the other hand feels great next to the skin but has tended to be either too warm or too delicate.
Traditionally, lighter weight cashmere has been knitted in single or double ply (ply being the size of the needle used for the knitting where more plys generally means heavier yarn and a warmer sweater). Double ply knitwear is the traditional slightly-too-warm-for-heated-rooms version that we know so well and single ply is unfortunately a bit too delicate for something that should ideally last a lifetime. There is however a newer double ply made with what are two single ply strands of yarn twisted together and then knitted with a double ply needle so it combines greater strength with a lighter weight that is better suited for spring.
In the photo, a double ply spring weight Inis Meáin sweater in 50% linen and 50% cashmere. Worn over a short sleeved polo on a 60 degree (15C) day, it is comfortable over a range of moderate temperatures.