Dating Systems
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A date written in a medieval Italian document does not necessarily mean what a modern reader assumes it means. This page sets out the conventions that must be established before any such date is used. For the technical vocabulary of medieval art and codicology, see the Glossary.
Claims are marked according to their evidential status:
- [D] documented — attested in a primary source
- [C] scholarly consensus
- [?] contested or variable — practice differs by period, chancery or scribe
The Problem
A medieval Italian document dated “10 February 1300” may belong to what a modern reader calls 1299, 1300 or 1301, depending on where it was written. The reason is that the year number did not change on 1 January in most of medieval Europe, and different cities changed it on different days. These conventions are the stili di datazione, styles of dating.
Two further variables compound the difficulty: the day of the month might be expressed by the Roman calendar or by the Bolognese system rather than by a simple number, and the year might be identified additionally or instead by an indiction, a regnal year, or a liturgical feast.
For an art historian the consequences are direct. An inscription on a pulpit, a payment in a communal ledger, a contract for an altarpiece and a chronicle notice of the same event may all carry different year numbers while referring to the same day. Reconciling them is not pedantry; it is the difference between a correct and an incorrect chronology of a workshop.
The Principal Styles
Circumcision style (stile della Circoncisione) — Year begins 1 January. Identical to modern usage. Increasingly common from the fourteenth century onward and standard in Italy after the reforms of the mid-eighteenth century. [D]
Nativity style (stile della Natività) — Year begins 25 December. The year number therefore runs one unit ahead of the modern year during the last seven days of December only. Widely used in the Empire, in much of northern Europe, and at various periods by the papal chancery. [C]
Florentine Incarnation style (stile fiorentino dell’Incarnazione, ab Incarnatione) — Year begins 25 March following the modern 1 January. The Florentine year number therefore lags one unit behind the modern year from 1 January to 24 March, and coincides with it from 25 March to 31 December. [D]
Pisan Incarnation style (stile pisano, calculus pisanus) — Year begins 25 March preceding the modern 1 January. The Pisan year number runs one unit ahead of the modern year from 25 March to 31 December, and coincides with it from 1 January to 24 March. [D]
Venetian style (more veneto, abbreviated m.v.) — Year begins 1 March. January and February therefore belong to the preceding year number. Venetian documents very frequently carry the abbreviation explicitly, which makes them, paradoxically, among the easiest to convert. [D]
Byzantine style — Year begins 1 September, with the year counted from the Creation (5509 BC). Standard in the Byzantine administration and in the Greek-speaking south of Italy. [C]
Easter style (mos gallicanus) — Year begins at Easter, a movable feast. Used chiefly by the French royal chancery. Because Easter falls between 22 March and 25 April, some calendar dates occur twice in one year-number and others not at all. Rare in Italy but encountered in documents of French provenance concerning Italian commissions. [C]
Pisan and Florentine: The Working Rule
The two Tuscan styles differ only in whether 25 March is taken as the beginning of the year ahead or the year behind. The consequence is simple and worth memorising:
For any given day, the Pisan year number is always exactly one higher than the Florentine year number.
Conversion to the modern year:
| Date falls between | Pisan document | Florentine document |
|---|---|---|
| 1 January – 24 March | modern year = as written | modern year = as written + 1 |
| 25 March – 31 December | modern year = as written − 1 | modern year = as written |
Worked examples:
- Pisa, 10 June 1300 → 10 June 1299 modern.
- Pisa, 10 February 1300 → 10 February 1300 modern.
- Florence, 10 February 1300 → 10 February 1301 modern.
- Florence, 10 June 1300 → 10 June 1300 modern.
Both styles were abolished in the Grand Duchy of Tuscany by decree of Francis Stephen of Lorraine in November 1749, with effect from 1 January 1750. [D]
The practical significance for this site’s period is considerable. Any date between 25 March and 31 December in a Pisan source — which includes the great majority of dated inscriptions on Pisan monuments — must be reduced by one year. Where an inscription is the only evidence for the date of a work, the style question is not a footnote but the whole argument. [?] Individual cases require verification against the specific documentary tradition; the practice of a cathedral opera is not automatically that of the commune or of a notary working in the same city.
Siena: A Case Requiring Caution
Siena is routinely listed in reference works as having used the Incarnation style beginning 25 March in the Florentine manner. That statement is broadly serviceable but should not be treated as a fixed rule. [?]
The reasons for caution:
- Sienese practice was not uniform across the whole period, and the Nativity style (25 December) is attested in Sienese material as well. [?]
- The two principal series of Sienese communal records, the Biccherna and the Gabella, were organised by semesters rather than by calendar years, with administrations turning over at fixed points in the year. Payments to artists must therefore be located within a semester first and converted second. [D]
- Ecclesiastical, notarial and communal scribes in the same city could follow different conventions in the same decades. [?]
The correct procedure for a Sienese document is therefore not to apply a rule but to establish the style of the specific series in question, using the internal evidence of the register itself — most reliably, the point at which the year number changes in a continuously dated run of entries. Where this cannot be established, the ambiguity should be stated in the catalogue entry rather than resolved silently.
There is no distinct “Sienese style” in the technical sense in which “Pisan style” and “Venetian style” are technical terms. The phrase, where it appears, is a convenience label and not a defined system. [?]
Indictions
The indiction is a fifteen-year fiscal cycle. It gives no absolute year but constrains one: a proposed year must yield the indiction number stated in the document, or the reading is wrong.
Calculation: (year + 3) ÷ 15; the remainder is the indiction, with remainder 0 meaning indiction 15.
Three variants differ in the day the indiction changes:
| Variant | Also called | Indiction begins |
|---|---|---|
| Greek / Byzantine | Constantinopolitan | 1 September |
| Bedan | Caesarean, imperial | 24 September |
| Roman | pontifical | 25 December or 1 January |
Because the indiction and the year style may change on different days, a document written in the autumn can legitimately carry a year number and an indiction that appear mismatched. This is a signal to check the style, not evidence of scribal error.
Days of the Month
Roman reckoning — Days are counted backwards from three fixed points: the Kalends (1st), the Nones (5th, or 7th in March, May, July, October) and the Ides (13th, or 15th in those same four months). Thus IV Kal. Apr. = 29 March, counting inclusively.
Bolognese reckoning (consuetudo bononiensis) — Days in the first half of the month are counted forwards from the 1st (mense intrante), those in the second half backwards from the last day (mense exeunte or stante). This is the commonest system in Italian notarial documents of the communal period and is a frequent source of silent error, because the inclusive convention followed varies. [?]
Feast dating — Documents frequently date by the liturgical calendar (in festo sancti Michaelis, feria secunda post Pascha). Fixed feasts are unproblematic. Movable feasts depend on Easter and require a paschal table, and local calendars differ in the feasts they observe and the dates they assign to them, so the calendar of the relevant diocese must be used.
Two Further Traps
Hours of the day — The ora italica counted twenty-four hours from sunset. A document, chronicle or inscription referring to an event “at the second hour” or “in the night of” a given date may straddle what a modern reader treats as two days. [C]
Julian, not Gregorian — All dates in this period are Julian. The reform of 1582 does not apply retroactively, and medieval dates should not be converted to proleptic Gregorian equivalents. Where an astronomical event (an eclipse, a comet) is used to fix a chronology, the conversion is made for that calculation only and stated explicitly. [C]
Practical Protocol
For any dated document or inscription cited on this site, the following are established and recorded before the date is used:
- Place of issue and the institution or chancery responsible.
- Style of the year in that institution’s practice for that decade — not merely the city’s general reputation.
- System used for the day (simple numeral, Roman, Bolognese, liturgical).
- Indiction, where given, as a cross-check.
- The converted date, given in the form: as written → modern equivalent, with the style named.
Dates are cited in the form 1259 (Pisan style 1260) or 1300/1301 (Florentine style) wherever the distinction bears on the argument. Where the style cannot be established, this is stated rather than assumed.
Standard Reference Works
For conversions and for the practice of individual cities, the standard tools are Cappelli’s Cronologia, cronografia e calendario perpetuo, Grotefend’s Taschenbuch der Zeitrechnung, and, for the technique of the medieval document more generally, the handbooks of Italian diplomatics. These are working instruments to be consulted case by case, not authorities to be cited in place of the primary source.